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2 weeks ago HTML Living Standard — Last Updated 23 August 2024
One-Page Version html.spec.whatwg.org
Multipage Version /multipage
Version for Web Devs /dev
PDF Version /print.pdf
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Table of contents
1 Introduction
2 Common infrastructure
3 Semantics, structure, and APIs of HTML documents
4 The elements of HTML
5 Microdata
6 User interaction
7 Loading web pages
8 Web application APIs
9 Communication
10 Web workers
11 Worklets
12 Web storage
13 The HTML syntax
14 The XML syntax
15 Rendering
16 Obsolete features
17 IANA considerations
Index
References
Acknowledgments
Intellectual property rights
Full table of contents
1 Introduction
1.1 Where does this specification fit?
1.2 Is this HTML5?
1.3 Background
1.4 Audience
1.5 Scope
1.6 History
1.7 Design notes
1.7.1 Serializability of script execution
1.7.2 Compliance with other specifications
1.7.3 Extensibility
1.8 HTML vs XML syntax
1.9 Structure of this specification
1.9.1 How to read this specification
1.9.2 Typographic conventions
1.10 A quick introduction to HTML
1.10.1 Writing secure applications with HTML
1.10.2 Common pitfalls to avoid when using the scripting APIs
1.10.3 How to catch mistakes when writing HTML: validators and conformance checkers
1.11 Conformance requirements for authors
1.11.1 Presentational markup
1.11.2 Syntax errors
1.11.3 Restrictions on content models and on attribute values
1.12 Suggested reading
2 Common infrastructure
2.1 Terminology
2.1.1 Parallelism
2.1.2 Resources
2.1.3 XML compatibility
2.1.4 DOM trees
2.1.5 Scripting
2.1.6 Plugins
2.1.7 Character encodings
2.1.8 Conformance classes
2.1.9 Dependencies
2.1.10 Extensibility
2.1.11 Interactions with XPath and XSLT
2.2 Policy-controlled features
2.3 Common microsyntaxes
2.3.1 Common parser idioms
2.3.2 Boolean attributes
2.3.3 Keywords and enumerated attributes
2.3.4 Numbers
2.3.4.1 Signed integers
2.3.4.2 Non-negative integers
2.3.4.3 Floating-point numbers
2.3.4.4 Percentages and lengths
2.3.4.5 Nonzero percentages and lengths
2.3.4.6 Lists of floating-point numbers
2.3.4.7 Lists of dimensions
2.3.5 Dates and times
2.3.5.1 Months
2.3.5.2 Dates
2.3.5.3 Yearless dates
2.3.5.4 Times
2.3.5.5 Local dates and times
2.3.5.6 Time zones
2.3.5.7 Global dates and times
2.3.5.8 Weeks
2.3.5.9 Durations
2.3.5.10 Vaguer moments in time
2.3.6 Colors
2.3.7 Space-separated tokens
2.3.8 Comma-separated tokens
2.3.9 References
2.3.10 Media queries
2.3.11 Unique internal values
2.4 URLs
2.4.1 Terminology
2.4.2 Parsing URLs
2.4.3 Dynamic changes to base URLs
2.5 Fetching resources
2.5.1 Terminology
2.5.2 Determining the type of a resource
2.5.3 Extracting character encodings from meta elements
2.5.4 CORS settings attributes
2.5.5 Referrer policy attributes
2.5.6 Nonce attributes
2.5.7 Lazy loading attributes
2.5.8 Blocking attributes
2.5.9 Fetch priority attributes
2.6 Common DOM interfaces
2.6.1 Reflecting content attributes in IDL attributes
2.6.2 Using reflect in specifications
2.6.3 Collections
2.6.3.1 The HTMLAllCollection interface
2.6.3.1.1 [[Call]] ( thisArgument, argumentsList )
2.6.3.2 The HTMLFormControlsCollection interface
2.6.3.3 The HTMLOptionsCollection interface
2.6.4 The DOMStringList interface
2.7 Safe passing of structured data
2.7.1 Serializable objects
2.7.2 Transferable objects
2.7.3 StructuredSerializeInternal ( value, forStorage [ , memory ] )
2.7.4 StructuredSerialize ( value )
2.7.5 StructuredSerializeForStorage ( value )
2.7.6 StructuredDeserialize ( serialized, targetRealm [ , memory ] )
2.7.7 StructuredSerializeWithTransfer ( value, transferList )
2.7.8 StructuredDeserializeWithTransfer ( serializeWithTransferResult, targetRealm )
2.7.9 Performing serialization and transferring from other specifications
2.7.10 Structured cloning API
3 Semantics, structure, and APIs of HTML documents
3.1 Documents
3.1.1 The Document object
3.1.2 The DocumentOrShadowRoot interface
3.1.3 Resource metadata management
3.1.4 Reporting document loading status
3.1.5 Render-blocking mechanism
3.1.6 DOM tree accessors
3.2 Elements
3.2.1 Semantics
3.2.2 Elements in the DOM
3.2.3 HTML element constructors
3.2.4 Element definitions
3.2.4.1 Attributes
3.2.5 Content models
3.2.5.1 The "nothing" content model
3.2.5.2 Kinds of content
3.2.5.2.1 Metadata content
3.2.5.2.2 Flow content
3.2.5.2.3 Sectioning content
3.2.5.2.4 Heading content
3.2.5.2.5 Phrasing content
3.2.5.2.6 Embedded content
3.2.5.2.7 Interactive content
3.2.5.2.8 Palpable content
3.2.5.2.9 Script-supporting elements
3.2.5.3 Transparent content models
3.2.5.4 Paragraphs
3.2.6 Global attributes
3.2.6.1 The title attribute
3.2.6.2 The lang and xml:lang attributes
3.2.6.3 The translate attribute
3.2.6.4 The dir attribute
3.2.6.5 The style attribute
3.2.6.6 Embedding custom non-visible data with the data-* attributes
3.2.7 The innerText and outerText properties
3.2.8 Requirements relating to the bidirectional algorithm
3.2.8.1 Authoring conformance criteria for bidirectional-algorithm formatting characters
3.2.8.2 User agent conformance criteria
3.2.9 Requirements related to ARIA and to platform accessibility APIs
4 The elements of HTML
4.1 The document element
4.1.1 The html element
4.2 Document metadata
4.2.1 The head element
4.2.2 The title element
4.2.3 The base element
4.2.4 The link element
4.2.4.1 Processing the media attribute
4.2.4.2 Processing the type attribute
4.2.4.3 Fetching and processing a resource from a link element
4.2.4.4 Processing Link headers
4.2.4.5 Early hints
4.2.4.6 Providing users with a means to follow hyperlinks created using the link element
4.2.5 The meta element
4.2.5.1 Standard metadata names
4.2.5.2 Other metadata names
4.2.5.3 Pragma directives
4.2.5.4 Specifying the document's character encoding
4.2.6 The style element
4.2.7 Interactions of styling and scripting
4.3 Sections
4.3.1 The body element
4.3.2 The article element
4.3.3 The section element
4.3.4 The nav element
4.3.5 The aside element
4.3.6 The h1, h2, h3, h4, h5, and h6 elements
4.3.7 The hgroup element
4.3.8 The header element
4.3.9 The footer element
4.3.10 The address element
4.3.11 Headings and outlines
4.3.11.1 Sample outlines
4.3.11.2 Exposing outlines to users
4.3.12 Usage summary
4.3.12.1 Article or section?
4.4 Grouping content
4.4.1 The p element
4.4.2 The hr element
4.4.3 The pre element
4.4.4 The blockquote element
4.4.5 The ol element
4.4.6 The ul element
4.4.7 The menu element
4.4.8 The li element
4.4.9 The dl element
4.4.10 The dt element
4.4.11 The dd element
4.4.12 The figure element
4.4.13 The figcaption element
4.4.14 The main element
4.4.15 The search element
4.4.16 The div element
4.5 Text-level semantics
4.5.1 The a element
4.5.2 The em element
4.5.3 The strong element
4.5.4 The small element
4.5.5 The s element
4.5.6 The cite element
4.5.7 The q element
4.5.8 The dfn element
4.5.9 The abbr element
4.5.10 The ruby element
4.5.11 The rt element
4.5.12 The rp element
4.5.13 The data element
4.5.14 The time element
4.5.15 The code element
4.5.16 The var element
4.5.17 The samp element
4.5.18 The kbd element
4.5.19 The sub and sup elements
4.5.20 The i element
4.5.21 The b element
4.5.22 The u element
4.5.23 The mark element
4.5.24 The bdi element
4.5.25 The bdo element
4.5.26 The span element
4.5.27 The br element
4.5.28 The wbr element
4.5.29 Usage summary
4.6 Links
4.6.1 Introduction
4.6.2 Links created by a and area elements
4.6.3 API for a and area elements
4.6.4 Following hyperlinks
4.6.5 Downloading resources
4.6.6 Hyperlink auditing
4.6.6.1 The Ping-From and Ping-To headers
4.6.7 Link types
4.6.7.1 Link type "alternate"
4.6.7.2 Link type "author"
4.6.7.3 Link type "bookmark"
4.6.7.4 Link type "canonical"
4.6.7.5 Link type "dns-prefetch"
4.6.7.6 Link type "expect"
4.6.7.7 Link type "external"
4.6.7.8 Link type "help"
4.6.7.9 Link type "icon"
4.6.7.10 Link type "license"
4.6.7.11 Link type "manifest"
4.6.7.12 Link type "modulepreload"
4.6.7.13 Link type "nofollow"
4.6.7.14 Link type "noopener"
4.6.7.15 Link type "noreferrer"
4.6.7.16 Link type "opener"
4.6.7.17 Link type "pingback"
4.6.7.18 Link type "preconnect"
4.6.7.19 Link type "prefetch"
4.6.7.20 Link type "preload"
4.6.7.21 Link type "privacy-policy"
4.6.7.22 Link type "search"
4.6.7.23 Link type "stylesheet"
4.6.7.24 Link type "tag"
4.6.7.25 Link Type "terms-of-service"
4.6.7.26 Sequential link types
4.6.7.26.1 Link type "next"
4.6.7.26.2 Link type "prev"
4.6.7.27 Other link types
4.7 Edits
4.7.1 The ins element
4.7.2 The del element
4.7.3 Attributes common to ins and del elements
4.7.4 Edits and paragraphs
4.7.5 Edits and lists
4.7.6 Edits and tables
4.8 Embedded content
4.8.1 The picture element
4.8.2 The source element
4.8.3 The img element
4.8.4 Images
4.8.4.1 Introduction
4.8.4.1.1 Adaptive images
4.8.4.2 Attributes common to source, img, and link elements
4.8.4.2.1 Srcset attributes
4.8.4.2.2 Sizes attributes
4.8.4.3 Processing model
4.8.4.3.1 When to obtain images
4.8.4.3.2 Reacting to DOM mutations
4.8.4.3.3 The list of available images
4.8.4.3.4 Decoding images
4.8.4.3.5 Updating the image data
4.8.4.3.6 Preparing an image for presentation
4.8.4.3.7 Selecting an image source
4.8.4.3.8 Creating a source set from attributes
4.8.4.3.9 Updating the source set
4.8.4.3.10 Parsing a srcset attribute
4.8.4.3.11 Parsing a sizes attribute
4.8.4.3.12 Normalizing the source densities
4.8.4.3.13 Reacting to environment changes
4.8.4.4 Requirements for providing text to act as an alternative for images
4.8.4.4.1 General guidelines
4.8.4.4.2 A link or button containing nothing but the image
4.8.4.4.3 A phrase or paragraph with an alternative graphical representation: charts, diagrams, graphs, maps, illustrations
4.8.4.4.4 A short phrase or label with an alternative graphical representation: icons, logos
4.8.4.4.5 Text that has been rendered to a graphic for typographical effect
4.8.4.4.6 A graphical representation of some of the surrounding text
4.8.4.4.7 Ancillary images
4.8.4.4.8 A purely decorative image that doesn't add any information
4.8.4.4.9 A group of images that form a single larger picture with no links
4.8.4.4.10 A group of images that form a single larger picture with links
4.8.4.4.11 A key part of the content
4.8.4.4.12 An image not intended for the user
4.8.4.4.13 An image in an email or private document intended for a specific person who is known to be able to view images
4.8.4.4.14 Guidance for markup generators
4.8.4.4.15 Guidance for conformance checkers
4.8.5 The iframe element
4.8.6 The embed element
4.8.7 The object element
4.8.8 The video element
4.8.9 The audio element
4.8.10 The track element
4.8.11 Media elements
4.8.11.1 Error codes
4.8.11.2 Location of the media resource
4.8.11.3 MIME types
4.8.11.4 Network states
4.8.11.5 Loading the media resource
4.8.11.6 Offsets into the media resource
4.8.11.7 Ready states
4.8.11.8 Playing the media resource
4.8.11.9 Seeking
4.8.11.10 Media resources with multiple media tracks
4.8.11.10.1 AudioTrackList and VideoTrackList objects
4.8.11.10.2 Selecting specific audio and video tracks declaratively
4.8.11.11 Timed text tracks
4.8.11.11.1 Text track model
4.8.11.11.2 Sourcing in-band text tracks
4.8.11.11.3 Sourcing out-of-band text tracks
4.8.11.11.4 Guidelines for exposing cues in various formats as text track cues
4.8.11.11.5 Text track API
4.8.11.11.6 Event handlers for objects of the text track APIs
4.8.11.11.7 Best practices for metadata text tracks
4.8.11.12 Identifying a track kind through a URL
4.8.11.13 User interface
4.8.11.14 Time ranges
4.8.11.15 The TrackEvent interface
4.8.11.16 Events summary
4.8.11.17 Security and privacy considerations
4.8.11.18 Best practices for authors using media elements
4.8.11.19 Best practices for implementers of media elements
4.8.12 The map element
4.8.13 The area element
4.8.14 Image maps
4.8.14.1 Authoring
4.8.14.2 Processing model
4.8.15 MathML
4.8.16 SVG
4.8.17 Dimension attributes
4.9 Tabular data
4.9.1 The table element
4.9.1.1 Techniques for describing tables
4.9.1.2 Techniques for table design
4.9.2 The caption element
4.9.3 The colgroup element
4.9.4 The col element
4.9.5 The tbody element
4.9.6 The thead element
4.9.7 The tfoot element
4.9.8 The tr element
4.9.9 The td element
4.9.10 The th element
4.9.11 Attributes common to td and th elements
4.9.12 Processing model
4.9.12.1 Forming a table
4.9.12.2 Forming relationships between data cells and header cells
4.9.13 Examples
4.10 Forms
4.10.1 Introduction
4.10.1.1 Writing a form's user interface
4.10.1.2 Implementing the server-side processing for a form
4.10.1.3 Configuring a form to communicate with a server
4.10.1.4 Client-side form validation
4.10.1.5 Enabling client-side automatic filling of form controls
4.10.1.6 Improving the user experience on mobile devices
4.10.1.7 The difference between the field type, the autofill field name, and the input modality
4.10.1.8 Date, time, and number formats
4.10.2 Categories
4.10.3 The form element
4.10.4 The label element
4.10.5 The input element
4.10.5.1 States of the type attribute
4.10.5.1.1 Hidden state (type=hidden)
4.10.5.1.2 Text (type=text) state and Search state (type=search)
4.10.5.1.3 Telephone state (type=tel)
4.10.5.1.4 URL state (type=url)
4.10.5.1.5 Email state (type=email)
4.10.5.1.6 Password state (type=password)
4.10.5.1.7 Date state (type=date)
4.10.5.1.8 Month state (type=month)
4.10.5.1.9 Week state (type=week)
4.10.5.1.10 Time state (type=time)
4.10.5.1.11 Local Date and Time state (type=datetime-local)
4.10.5.1.12 Number state (type=number)
4.10.5.1.13 Range state (type=range)
4.10.5.1.14 Color state (type=color)
4.10.5.1.15 Checkbox state (type=checkbox)
4.10.5.1.16 Radio Button state (type=radio)
4.10.5.1.17 File Upload state (type=file)
4.10.5.1.18 Submit Button state (type=submit)
4.10.5.1.19 Image Button state (type=image)
4.10.5.1.20 Reset Button state (type=reset)
4.10.5.1.21 Button state (type=button)
4.10.5.2 Implementation notes regarding localization of form controls
4.10.5.3 Common input element attributes
4.10.5.3.1 The maxlength and minlength attributes
4.10.5.3.2 The size attribute
4.10.5.3.3 The readonly attribute
4.10.5.3.4 The required attribute
4.10.5.3.5 The multiple attribute
4.10.5.3.6 The pattern attribute
4.10.5.3.7 The min and max attributes
4.10.5.3.8 The step attribute
4.10.5.3.9 The list attribute
4.10.5.3.10 The placeholder attribute
4.10.5.4 Common input element APIs
4.10.5.5 Common event behaviors
4.10.6 The button element
4.10.7 The select element
4.10.8 The datalist element
4.10.9 The optgroup element
4.10.10 The option element
4.10.11 The textarea element
4.10.12 The output element
4.10.13 The progress element
4.10.14 The meter element
4.10.15 The fieldset element
4.10.16 The legend element
4.10.17 Form control infrastructure
4.10.17.1 A form control's value
4.10.17.2 Mutability
4.10.17.3 Association of controls and forms
4.10.18 Attributes common to form controls
4.10.18.1 Naming form controls: the name attribute
4.10.18.2 Submitting element directionality: the dirname attribute
4.10.18.3 Limiting user input length: the maxlength attribute
4.10.18.4 Setting minimum input length requirements: the minlength attribute
4.10.18.5 Enabling and disabling form controls: the disabled attribute
4.10.18.6 Form submission attributes
4.10.18.7 Autofill
4.10.18.7.1 Autofilling form controls: the autocomplete attribute
4.10.18.7.2 Processing model
4.10.19 APIs for the text control selections
4.10.20 Constraints
4.10.20.1 Definitions
4.10.20.2 Constraint validation
4.10.20.3 The constraint validation API
4.10.20.4 Security
4.10.21 Form submission
4.10.21.1 Introduction
4.10.21.2 Implicit submission
4.10.21.3 Form submission algorithm
4.10.21.4 Constructing the entry list
4.10.21.5 Selecting a form submission encoding
4.10.21.6 Converting an entry list to a list of name-value pairs
4.10.21.7 URL-encoded form data
4.10.21.8 Multipart form data
4.10.21.9 Plain text form data
4.10.21.10 The SubmitEvent interface
4.10.21.11 The FormDataEvent interface
4.10.22 Resetting a form
4.11 Interactive elements
4.11.1 The details element
4.11.2 The summary element
4.11.3 Commands
4.11.3.1 Facets
4.11.3.2 Using the a element to define a command
4.11.3.3 Using the button element to define a command
4.11.3.4 Using the input element to define a command
4.11.3.5 Using the option element to define a command
4.11.3.6 Using the accesskey attribute on a legend element to define a command
4.11.3.7 Using the accesskey attribute to define a command on other elements
4.11.4 The dialog element
4.12 Scripting
4.12.1 The script element
4.12.1.1 Processing model
4.12.1.2 Scripting languages
4.12.1.3 Restrictions for contents of script elements
4.12.1.4 Inline documentation for external scripts
4.12.1.5 Interaction of script elements and XSLT
4.12.2 The noscript element
4.12.3 The template element
4.12.3.1 Interaction of template elements with XSLT and XPath
4.12.4 The slot element
4.12.5 The canvas element
4.12.5.1 The 2D rendering context
4.12.5.1.1 Implementation notes
4.12.5.1.2 The canvas state
4.12.5.1.3 Line styles
4.12.5.1.4 Text styles
4.12.5.1.5 Building paths
4.12.5.1.6 Path2D objects
4.12.5.1.7 Transformations
4.12.5.1.8 Image sources for 2D rendering contexts
4.12.5.1.9 Fill and stroke styles
4.12.5.1.10 Drawing rectangles to the bitmap
4.12.5.1.11 Drawing text to the bitmap
4.12.5.1.12 Drawing paths to the canvas
4.12.5.1.13 Drawing focus rings
4.12.5.1.14 Drawing images
4.12.5.1.15 Pixel manipulation
4.12.5.1.16 Compositing
4.12.5.1.17 Image smoothing
4.12.5.1.18 Shadows
4.12.5.1.19 Filters
4.12.5.1.20 Working with externally-defined SVG filters
4.12.5.1.21 Drawing model
4.12.5.1.22 Best practices
4.12.5.1.23 Examples
4.12.5.2 The ImageBitmap rendering context
4.12.5.2.1 Introduction
4.12.5.2.2 The ImageBitmapRenderingContext interface
4.12.5.3 The OffscreenCanvas interface
4.12.5.3.1 The offscreen 2D rendering context
4.12.5.4 Color spaces and color space conversion
4.12.5.5 Serializing bitmaps to a file
4.12.5.6 Security with canvas elements
4.12.5.7 Premultiplied alpha and the 2D rendering context
4.13 Custom elements
4.13.1 Introduction
4.13.1.1 Creating an autonomous custom element
4.13.1.2 Creating a form-associated custom element
4.13.1.3 Creating a custom element with default accessible roles, states, and properties
4.13.1.4 Creating a customized built-in element
4.13.1.5 Drawbacks of autonomous custom elements
4.13.1.6 Upgrading elements after their creation
4.13.1.7 Exposing custom element states
4.13.2 Requirements for custom element constructors and reactions
4.13.3 Core concepts
4.13.4 The CustomElementRegistry interface
4.13.5 Upgrades
4.13.6 Custom element reactions
4.13.7 Element internals
4.13.7.1 The ElementInternals interface
4.13.7.2 Shadow root access
4.13.7.3 Form-associated custom elements
4.13.7.4 Accessibility semantics
4.13.7.5 Custom state pseudo-class
4.14 Common idioms without dedicated elements
4.14.1 Breadcrumb navigation
4.14.2 Tag clouds
4.14.3 Conversations
4.14.4 Footnotes
4.15 Disabled elements
4.16 Matching HTML elements using selectors and CSS
4.16.1 Case-sensitivity of the CSS 'attr()' function
4.16.2 Case-sensitivity of selectors
4.16.3 Pseudo-classes
5 Microdata
5.1 Introduction
5.1.1 Overview
5.1.2 The basic syntax
5.1.3 Typed items
5.1.4 Global identifiers for items
5.1.5 Selecting names when defining vocabularies
5.2 Encoding microdata
5.2.1 The microdata model
5.2.2 Items
5.2.3 Names: the itemprop attribute
5.2.4 Values
5.2.5 Associating names with items
5.2.6 Microdata and other namespaces
5.3 Sample microdata vocabularies
5.3.1 vCard
5.3.1.1 Conversion to vCard
5.3.1.2 Examples
5.3.2 vEvent
5.3.2.1 Conversion to iCalendar
5.3.2.2 Examples
5.3.3 Licensing works
5.3.3.1 Examples
5.4 Converting HTML to other formats
5.4.1 JSON
6 User interaction
6.1 The hidden attribute
6.2 Page visibility
6.2.1 The VisibilityStateEntry interface
6.3 Inert subtrees
6.3.1 Modal dialogs and inert subtrees
6.3.2 The inert attribute
6.4 Tracking user activation
6.4.1 Data model
6.4.2 Processing model
6.4.3 APIs gated by user activation
6.4.4 The UserActivation interface
6.4.5 User agent automation
6.5 Activation behavior of elements
6.5.1 The ToggleEvent interface
6.6 Focus
6.6.1 Introduction
6.6.2 Data model
6.6.3 The tabindex attribute
6.6.4 Processing model
6.6.5 Sequential focus navigation
6.6.6 Focus management APIs
6.6.7 The autofocus attribute
6.7 Assigning keyboard shortcuts
6.7.1 Introduction
6.7.2 The accesskey attribute
6.7.3 Processing model
6.8 Editing
6.8.1 Making document regions editable: The contenteditable content attribute
6.8.2 Making entire documents editable: the designMode getter and setter
6.8.3 Best practices for in-page editors
6.8.4 Editing APIs
6.8.5 Spelling and grammar checking
6.8.6 Writing suggestions
6.8.7 Autocapitalization
6.8.8 Input modalities: the inputmode attribute
6.8.9 Input modalities: the enterkeyhint attribute
6.9 Find-in-page
6.9.1 Introduction
6.9.2 Interaction with details and hidden=until-found
6.9.3 Interaction with selection
6.10 Close requests and close watchers
6.10.1 Close requests
6.10.2 Close watcher infrastructure
6.10.3 The CloseWatcher interface
6.11 Drag and drop
6.11.1 Introduction
6.11.2 The drag data store
6.11.3 The DataTransfer interface
6.11.3.1 The DataTransferItemList interface
6.11.3.2 The DataTransferItem interface
6.11.4 The DragEvent interface
6.11.5 Processing model
6.11.6 Events summary
6.11.7 The draggable attribute
6.11.8 Security risks in the drag-and-drop model
6.12 The popover attribute
6.12.1 The popover target attributes
6.12.2 Popover light dismiss
7 Loading web pages
7.1 Supporting concepts
7.1.1 Origins
7.1.1.1 Sites
7.1.1.2 Relaxing the same-origin restriction
7.1.2 Origin-keyed agent clusters
7.1.3 Cross-origin opener policies
7.1.3.1 The headers
7.1.3.2 Browsing context group switches due to cross-origin opener policy
7.1.3.3 Reporting
7.1.4 Cross-origin embedder policies
7.1.4.1 The headers
7.1.4.2 Embedder policy checks
7.1.5 Sandboxing
7.1.6 Policy containers
7.2 APIs related to navigation and session history
7.2.1 Security infrastructure for Window, WindowProxy, and Location objects
7.2.1.1 Integration with IDL
7.2.1.2 Shared internal slot: [[CrossOriginPropertyDescriptorMap]]
7.2.1.3 Shared abstract operations
7.2.1.3.1 CrossOriginProperties ( O )
7.2.1.3.2 CrossOriginPropertyFallback ( P )
7.2.1.3.3 IsPlatformObjectSameOrigin ( O )
7.2.1.3.4 CrossOriginGetOwnPropertyHelper ( O, P )
7.2.1.3.5 CrossOriginGet ( O, P, Receiver )
7.2.1.3.6 CrossOriginSet ( O, P, V, Receiver )
7.2.1.3.7 CrossOriginOwnPropertyKeys ( O )
7.2.2 The Window object
7.2.2.1 Opening and closing windows
7.2.2.2 Indexed access on the Window object
7.2.2.3 Named access on the Window object
7.2.2.4 Accessing related windows
7.2.2.5 Historical browser interface element APIs
7.2.2.6 Script settings for Window objects
7.2.3 The WindowProxy exotic object
7.2.3.1 [[GetPrototypeOf]] ( )
7.2.3.2 [[SetPrototypeOf]] ( V )
7.2.3.3 [[IsExtensible]] ( )
7.2.3.4 [[PreventExtensions]] ( )
7.2.3.5 [[GetOwnProperty]] ( P )
7.2.3.6 [[DefineOwnProperty]] ( P, Desc )
7.2.3.7 [[Get]] ( P, Receiver )
7.2.3.8 [[Set]] ( P, V, Receiver )
7.2.3.9 [[Delete]] ( P )
7.2.3.10 [[OwnPropertyKeys]] ( )
7.2.4 The Location interface
7.2.4.1 [[GetPrototypeOf]] ( )
7.2.4.2 [[SetPrototypeOf]] ( V )
7.2.4.3 [[IsExtensible]] ( )
7.2.4.4 [[PreventExtensions]] ( )
7.2.4.5 [[GetOwnProperty]] ( P )
7.2.4.6 [[DefineOwnProperty]] ( P, Desc )
7.2.4.7 [[Get]] ( P, Receiver )
7.2.4.8 [[Set]] ( P, V, Receiver )
7.2.4.9 [[Delete]] ( P )
7.2.4.10 [[OwnPropertyKeys]] ( )
7.2.5 The History interface
7.2.6 The navigation API
7.2.6.1 Introduction
7.2.6.2 The Navigation interface
7.2.6.3 Core infrastructure
7.2.6.4 Initializing and updating the entry list
7.2.6.5 The NavigationHistoryEntry interface
7.2.6.6 The history entry list
7.2.6.7 Initiating navigations
7.2.6.8 Ongoing navigation tracking
7.2.6.9 The NavigationActivation interface
7.2.6.10 The navigate event
7.2.6.10.1 The NavigateEvent interface
7.2.6.10.2 The NavigationDestination interface
7.2.6.10.3 Firing the event
7.2.6.10.4 Scroll and focus behavior
7.2.7 Event interfaces
7.2.7.1 The NavigationCurrentEntryChangeEvent interface
7.2.7.2 The PopStateEvent interface
7.2.7.3 The HashChangeEvent interface
7.2.7.4 The PageSwapEvent interface
7.2.7.5 The PageRevealEvent interface
7.2.7.6 The PageTransitionEvent interface
7.2.7.7 The BeforeUnloadEvent interface
7.2.8 The NotRestoredReasons interface
7.3 Infrastructure for sequences of documents
7.3.1 Navigables
7.3.1.1 Traversable navigables
7.3.1.2 Top-level traversables
7.3.1.3 Child navigables
7.3.1.4 Jake diagrams
7.3.1.5 Related navigable collections
7.3.1.6 Navigable destruction
7.3.1.7 Navigable target names
7.3.2 Browsing contexts
7.3.2.1 Creating browsing contexts
7.3.2.2 Related browsing contexts
7.3.2.3 Groupings of browsing contexts
7.3.3 Fully active documents
7.4 Navigation and session history
7.4.1 Session history
7.4.1.1 Session history entries
7.4.1.2 Document state
7.4.1.3 Centralized modifications of session history
7.4.1.4 Low-level operations on session history
7.4.2 Navigation
7.4.2.1 Supporting concepts
7.4.2.2 Beginning navigation
7.4.2.3 Ending navigation
7.4.2.3.1 The usual cross-document navigation case
7.4.2.3.2 The javascript: URL special case
7.4.2.3.3 Fragment navigations
7.4.2.3.4 Non-fetch schemes and external software
7.4.2.4 Preventing navigation
7.4.2.5 Aborting navigation
7.4.3 Reloading and traversing
7.4.4 Non-fragment synchronous "navigations"
7.4.5 Populating a session history entry
7.4.6 Applying the history step
7.4.6.1 Updating the traversable
7.4.6.2 Updating the document
7.4.6.3 Revealing the document
7.4.6.4 Scrolling to a fragment
7.4.6.5 Persisted history entry state
7.5 Document lifecycle
7.5.1 Shared document creation infrastructure
7.5.2 Loading HTML documents
7.5.3 Loading XML documents
7.5.4 Loading text documents
7.5.5 Loading multipart/x-mixed-replace documents
7.5.6 Loading media documents
7.5.7 Loading a document for inline content that doesn't have a DOM
7.5.8 Finishing the loading process
7.5.9 Unloading documents
7.5.10 Destroying documents
7.5.11 Aborting a document load
7.6 The X-Frame-Options header
7.7 The Refresh header
7.8 Browser user interface considerations
8 Web application APIs
8.1 Scripting
8.1.1 Introduction
8.1.2 Agents and agent clusters
8.1.2.1 Integration with the JavaScript agent formalism
8.1.2.2 Integration with the JavaScript agent cluster formalism
8.1.3 Realms and their counterparts
8.1.3.1 Environments
8.1.3.2 Environment settings objects
8.1.3.3 Realms, settings objects, and global objects
8.1.3.3.1 Entry
8.1.3.3.2 Incumbent
8.1.3.3.3 Current
8.1.3.3.4 Relevant
8.1.3.4 Enabling and disabling scripting
8.1.3.5 Secure contexts
8.1.4 Script processing model
8.1.4.1 Scripts
8.1.4.2 Fetching scripts
8.1.4.3 Creating scripts
8.1.4.4 Calling scripts
8.1.4.5 Killing scripts
8.1.4.6 Runtime script errors
8.1.4.7 Unhandled promise rejections
8.1.4.8 Import map parse results
8.1.5 Module specifier resolution
8.1.5.1 The resolution algorithm
8.1.5.2 Import maps
8.1.5.3 Import map processing model
8.1.6 JavaScript specification host hooks
8.1.6.1 HostEnsureCanAddPrivateElement(O)
8.1.6.2 HostEnsureCanCompileStrings(realm, parameterStrings, bodyString, codeString, compilationType, parameterArgs, bodyArg)
8.1.6.3 HostGetCodeForEval(argument)
8.1.6.4 HostPromiseRejectionTracker(promise, operation)
8.1.6.5 HostSystemUTCEpochNanoseconds(global)
8.1.6.6 Job-related host hooks
8.1.6.6.1 HostCallJobCallback(callback, V, argumentsList)
8.1.6.6.2 HostEnqueueFinalizationRegistryCleanupJob(finalizationRegistry)
8.1.6.6.3 HostEnqueueGenericJob(job, realm)
8.1.6.6.4 HostEnqueuePromiseJob(job, realm)
8.1.6.6.5 HostEnqueueTimeoutJob(job, realm, milliseconds)
8.1.6.6.6 HostMakeJobCallback(callable)
8.1.6.7 Module-related host hooks
8.1.6.7.1 HostGetImportMetaProperties(moduleRecord)
8.1.6.7.2 HostGetSupportedImportAttributes()
8.1.6.7.3 HostLoadImportedModule(referrer, moduleRequest, loadState, payload)
8.1.7 Event loops
8.1.7.1 Definitions
8.1.7.2 Queuing tasks
8.1.7.3 Processing model
8.1.7.4 Generic task sources
8.1.7.5 Dealing with the event loop from other specifications
8.1.8 Events
8.1.8.1 Event handlers
8.1.8.2 Event handlers on elements, Document objects, and Window objects
8.1.8.2.1 IDL definitions
8.1.8.3 Event firing
8.2 The WindowOrWorkerGlobalScope mixin
8.3 Base64 utility methods
8.4 Dynamic markup insertion
8.4.1 Opening the input stream
8.4.2 Closing the input stream
8.4.3 document.write()
8.4.4 document.writeln()
8.5 DOM parsing and serialization APIs
8.5.1 The DOMParser interface
8.5.2 Unsafe HTML parsing methods
8.5.3 HTML serialization methods
8.5.4 The innerHTML property
8.5.5 The outerHTML property
8.5.6 The insertAdjacentHTML() method
8.5.7 The createContextualFragment() method
8.6 Timers
8.7 Microtask queuing
8.8 User prompts
8.8.1 Simple dialogs
8.8.2 Printing
8.9 System state and capabilities
8.9.1 The Navigator object
8.9.1.1 Client identification
8.9.1.2 Language preferences
8.9.1.3 Browser state
8.9.1.4 Custom scheme handlers: the registerProtocolHandler() method
8.9.1.4.1 Security and privacy
8.9.1.4.2 User agent automation
8.9.1.5 Cookies
8.9.1.6 PDF viewing support
8.10 Images
8.11 Animation frames
9 Communication
9.1 The MessageEvent interface
9.2 Server-sent events
9.2.1 Introduction
9.2.2 The EventSource interface
9.2.3 Processing model
9.2.4 The Last-Event-ID header
9.2.5 Parsing an event stream
9.2.6 Interpreting an event stream
9.2.7 Authoring notes
9.2.8 Connectionless push and other features
9.2.9 Garbage collection
9.2.10 Implementation advice
9.3 Cross-document messaging
9.3.1 Introduction
9.3.2 Security
9.3.2.1 Authors
9.3.2.2 User agents
9.3.3 Posting messages
9.4 Channel messaging
9.4.1 Introduction
9.4.1.1 Examples
9.4.1.2 Ports as the basis of an object-capability model on the web
9.4.1.3 Ports as the basis of abstracting out service implementations
9.4.2 Message channels
9.4.3 Message ports
9.4.4 Ports and garbage collection
9.5 Broadcasting to other browsing contexts
10 Web workers
10.1 Introduction
10.1.1 Scope
10.1.2 Examples
10.1.2.1 A background number-crunching worker
10.1.2.2 Using a JavaScript module as a worker
10.1.2.3 Shared workers introduction
10.1.2.4 Shared state using a shared worker
10.1.2.5 Delegation
10.1.2.6 Providing libraries
10.1.3 Tutorials
10.1.3.1 Creating a dedicated worker
10.1.3.2 Communicating with a dedicated worker
10.1.3.3 Shared workers
10.2 Infrastructure
10.2.1 The global scope
10.2.1.1 The WorkerGlobalScope common interface
10.2.1.2 Dedicated workers and the DedicatedWorkerGlobalScope interface
10.2.1.3 Shared workers and the SharedWorkerGlobalScope interface
10.2.2 The event loop
10.2.3 The worker's lifetime
10.2.4 Processing model
10.2.5 Runtime script errors
10.2.6 Creating workers
10.2.6.1 The AbstractWorker mixin
10.2.6.2 Script settings for workers
10.2.6.3 Dedicated workers and the Worker interface
10.2.6.4 Shared workers and the SharedWorker interface
10.2.7 Concurrent hardware capabilities
10.3 APIs available to workers
10.3.1 Importing scripts and libraries
10.3.2 The WorkerNavigator interface
10.3.3 The WorkerLocation interface
11 Worklets
11.1 Introduction
11.1.1 Motivations
11.1.2 Code idempotence
11.1.3 Speculative evaluation
11.2 Examples
11.2.1 Loading scripts
11.2.2 Registering a class and invoking its methods
11.3 Infrastructure
11.3.1 The global scope
11.3.1.1 Agents and event loops
11.3.1.2 Creation and termination
11.3.1.3 Script settings for worklets
11.3.2 The Worklet class
11.3.3 The worklet's lifetime
12 Web storage
12.1 Introduction
12.2 The API
12.2.1 The Storage interface
12.2.2 The sessionStorage getter
12.2.3 The localStorage getter
12.2.4 The StorageEvent interface
12.3 Privacy
12.3.1 User tracking
12.3.2 Sensitivity of data
12.4 Security
12.4.1 DNS spoofing attacks
12.4.2 Cross-directory attacks
12.4.3 Implementation risks
13 The HTML syntax
13.1 Writing HTML documents
13.1.1 The DOCTYPE
13.1.2 Elements
13.1.2.1 Start tags
13.1.2.2 End tags
13.1.2.3 Attributes
13.1.2.4 Optional tags
13.1.2.5 Restrictions on content models
13.1.2.6 Restrictions on the contents of raw text and escapable raw text elements
13.1.3 Text
13.1.3.1 Newlines
13.1.4 Character references
13.1.5 CDATA sections
13.1.6 Comments
13.2 Parsing HTML documents
13.2.1 Overview of the parsing model
13.2.2 Parse errors
13.2.3 The input byte stream
13.2.3.1 Parsing with a known character encoding
13.2.3.2 Determining the character encoding
13.2.3.3 Character encodings
13.2.3.4 Changing the encoding while parsing
13.2.3.5 Preprocessing the input stream
13.2.4 Parse state
13.2.4.1 The insertion mode
13.2.4.2 The stack of open elements
13.2.4.3 The list of active formatting elements
13.2.4.4 The element pointers
13.2.4.5 Other parsing state flags
13.2.5 Tokenization
13.2.5.1 Data state
13.2.5.2 RCDATA state
13.2.5.3 RAWTEXT state
13.2.5.4 Script data state
13.2.5.5 PLAINTEXT state
13.2.5.6 Tag open state
13.2.5.7 End tag open state
13.2.5.8 Tag name state
13.2.5.9 RCDATA less-than sign state
13.2.5.10 RCDATA end tag open state
13.2.5.11 RCDATA end tag name state
13.2.5.12 RAWTEXT less-than sign state
13.2.5.13 RAWTEXT end tag open state
13.2.5.14 RAWTEXT end tag name state
13.2.5.15 Script data less-than sign state
13.2.5.16 Script data end tag open state
13.2.5.17 Script data end tag name state
13.2.5.18 Script data escape start state
13.2.5.19 Script data escape start dash state
13.2.5.20 Script data escaped state
13.2.5.21 Script data escaped dash state
13.2.5.22 Script data escaped dash dash state
13.2.5.23 Script data escaped less-than sign state
13.2.5.24 Script data escaped end tag open state
13.2.5.25 Script data escaped end tag name state
13.2.5.26 Script data double escape start state
13.2.5.27 Script data double escaped state
13.2.5.28 Script data double escaped dash state
13.2.5.29 Script data double escaped dash dash state
13.2.5.30 Script data double escaped less-than sign state
13.2.5.31 Script data double escape end state
13.2.5.32 Before attribute name state
13.2.5.33 Attribute name state
13.2.5.34 After attribute name state
13.2.5.35 Before attribute value state
13.2.5.36 Attribute value (double-quoted) state
13.2.5.37 Attribute value (single-quoted) state
13.2.5.38 Attribute value (unquoted) state
13.2.5.39 After attribute value (quoted) state
13.2.5.40 Self-closing start tag state
13.2.5.41 Bogus comment state
13.2.5.42 Markup declaration open state
13.2.5.43 Comment start state
13.2.5.44 Comment start dash state
13.2.5.45 Comment state
13.2.5.46 Comment less-than sign state
13.2.5.47 Comment less-than sign bang state
13.2.5.48 Comment less-than sign bang dash state
13.2.5.49 Comment less-than sign bang dash dash state
13.2.5.50 Comment end dash state
13.2.5.51 Comment end state
13.2.5.52 Comment end bang state
13.2.5.53 DOCTYPE state
13.2.5.54 Before DOCTYPE name state
13.2.5.55 DOCTYPE name state
13.2.5.56 After DOCTYPE name state
13.2.5.57 After DOCTYPE public keyword state
13.2.5.58 Before DOCTYPE public identifier state
13.2.5.59 DOCTYPE public identifier (double-quoted) state
13.2.5.60 DOCTYPE public identifier (single-quoted) state
13.2.5.61 After DOCTYPE public identifier state
13.2.5.62 Between DOCTYPE public and system identifiers state
13.2.5.63 After DOCTYPE system keyword state
13.2.5.64 Before DOCTYPE system identifier state
13.2.5.65 DOCTYPE system identifier (double-quoted) state
13.2.5.66 DOCTYPE system identifier (single-quoted) state
13.2.5.67 After DOCTYPE system identifier state
13.2.5.68 Bogus DOCTYPE state
13.2.5.69 CDATA section state
13.2.5.70 CDATA section bracket state
13.2.5.71 CDATA section end state
13.2.5.72 Character reference state
13.2.5.73 Named character reference state
13.2.5.74 Ambiguous ampersand state
13.2.5.75 Numeric character reference state
13.2.5.76 Hexadecimal character reference start state
13.2.5.77 Decimal character reference start state
13.2.5.78 Hexadecimal character reference state
13.2.5.79 Decimal character reference state
13.2.5.80 Numeric character reference end state
13.2.6 Tree construction
13.2.6.1 Creating and inserting nodes
13.2.6.2 Parsing elements that contain only text
13.2.6.3 Closing elements that have implied end tags
13.2.6.4 The rules for parsing tokens in HTML content
13.2.6.4.1 The "initial" insertion mode
13.2.6.4.2 The "before html" insertion mode
13.2.6.4.3 The "before head" insertion mode
13.2.6.4.4 The "in head" insertion mode
13.2.6.4.5 The "in head noscript" insertion mode
13.2.6.4.6 The "after head" insertion mode
13.2.6.4.7 The "in body" insertion mode
13.2.6.4.8 The "text" insertion mode
13.2.6.4.9 The "in table" insertion mode
13.2.6.4.10 The "in table text" insertion mode
13.2.6.4.11 The "in caption" insertion mode
13.2.6.4.12 The "in column group" insertion mode
13.2.6.4.13 The "in table body" insertion mode
13.2.6.4.14 The "in row" insertion mode
13.2.6.4.15 The "in cell" insertion mode
13.2.6.4.16 The "in select" insertion mode
13.2.6.4.17 The "in select in table" insertion mode
13.2.6.4.18 The "in template" insertion mode
13.2.6.4.19 The "after body" insertion mode
13.2.6.4.20 The "in frameset" insertion mode
13.2.6.4.21 The "after frameset" insertion mode
13.2.6.4.22 The "after after body" insertion mode
13.2.6.4.23 The "after after frameset" insertion mode
13.2.6.5 The rules for parsing tokens in foreign content
13.2.7 The end
13.2.8 Speculative HTML parsing
13.2.9 Coercing an HTML DOM into an infoset
13.2.10 An introduction to error handling and strange cases in the parser
13.2.10.1 Misnested tags:
13.2.10.2 Misnested tags:
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Issues for Tests ongoing work Table of contents 1 Introduction 2 Common infrastructure 3 Semantics, structure, and APIs of HTML documents 4 The elements of HTML 5 Microdata 6 User interaction 7 Loading web pages 8 Web application APIs 9 Communication 10 Web workers 11 Worklets 12 Web storage 13 The HTML syntax 14 The XML syntax 15 Rendering 16 Obsolete features 17 IANA considerations Index References Acknowledgments Intellectual property rights Full table of contents 1 Introduction 1.1 Where does this specification fit? 1.2 Is this HTML5? 1.3 Background 1.4 Audience 1.5 Scope 1.6 History 1.7 Design notes 1.7.1 Serializability of script execution 1.7.2 Compliance with other specifications 1.7.3 Extensibility 1.8 HTML vs XML syntax 1.9 Structure of this specification 1.9.1 How to read this specification 1.9.2 Typographic conventions 1.10 A quick introduction to HTML 1.10.1 Writing secure applications with HTML 1.10.2 Common pitfalls to avoid when using the scripting APIs 1.10.3 How to catch mistakes when writing HTML: validators and conformance checkers 1.11 Conformance requirements for authors 1.11.1 Presentational markup 1.11.2 Syntax errors 1.11.3 Restrictions on content models and on attribute values 1.12 Suggested reading 2 Common infrastructure 2.1 Terminology 2.1.1 Parallelism 2.1.2 Resources 2.1.3 XML compatibility 2.1.4 DOM trees 2.1.5 Scripting 2.1.6 Plugins 2.1.7 Character encodings 2.1.8 Conformance classes 2.1.9 Dependencies 2.1.10 Extensibility 2.1.11 Interactions with XPath and XSLT 2.2 Policy-controlled features 2.3 Common microsyntaxes 2.3.1 Common parser idioms 2.3.2 Boolean attributes 2.3.3 Keywords and enumerated attributes 2.3.4 Numbers 2.3.4.1 Signed integers 2.3.4.2 Non-negative integers 2.3.4.3 Floating-point numbers 2.3.4.4 Percentages and lengths 2.3.4.5 Nonzero percentages and lengths 2.3.4.6 Lists of floating-point numbers 2.3.4.7 Lists of dimensions 2.3.5 Dates and times 2.3.5.1 Months 2.3.5.2 Dates 2.3.5.3 Yearless dates 2.3.5.4 Times 2.3.5.5 Local dates and times 2.3.5.6 Time zones 2.3.5.7 Global dates and times 2.3.5.8 Weeks 2.3.5.9 Durations 2.3.5.10 Vaguer moments in time 2.3.6 Colors 2.3.7 Space-separated tokens 2.3.8 Comma-separated tokens 2.3.9 References 2.3.10 Media queries 2.3.11 Unique internal values 2.4 URLs 2.4.1 Terminology 2.4.2 Parsing URLs 2.4.3 Dynamic changes to base URLs 2.5 Fetching resources 2.5.1 Terminology 2.5.2 Determining the type of a resource 2.5.3 Extracting character encodings from meta elements 2.5.4 CORS settings attributes 2.5.5 Referrer policy attributes 2.5.6 Nonce attributes 2.5.7 Lazy loading attributes 2.5.8 Blocking attributes 2.5.9 Fetch priority attributes 2.6 Common DOM interfaces 2.6.1 Reflecting content attributes in IDL attributes 2.6.2 Using reflect in specifications 2.6.3 Collections 2.6.3.1 The HTMLAllCollection interface 2.6.3.1.1 [[Call]] ( thisArgument, argumentsList ) 2.6.3.2 The HTMLFormControlsCollection interface 2.6.3.3 The HTMLOptionsCollection interface 2.6.4 The DOMStringList interface 2.7 Safe passing of structured data 2.7.1 Serializable objects 2.7.2 Transferable objects 2.7.3 StructuredSerializeInternal ( value, forStorage [ , memory ] ) 2.7.4 StructuredSerialize ( value ) 2.7.5 StructuredSerializeForStorage ( value ) 2.7.6 StructuredDeserialize ( serialized, targetRealm [ , memory ] ) 2.7.7 StructuredSerializeWithTransfer ( value, transferList ) 2.7.8 StructuredDeserializeWithTransfer ( serializeWithTransferResult, targetRealm ) 2.7.9 Performing serialization and transferring from other specifications 2.7.10 Structured cloning API 3 Semantics, structure, and APIs of HTML documents 3.1 Documents 3.1.1 The Document object 3.1.2 The DocumentOrShadowRoot interface 3.1.3 Resource metadata management 3.1.4 Reporting document loading status 3.1.5 Render-blocking mechanism 3.1.6 DOM tree accessors 3.2 Elements 3.2.1 Semantics 3.2.2 Elements in the DOM 3.2.3 HTML element constructors 3.2.4 Element definitions 3.2.4.1 Attributes 3.2.5 Content models 3.2.5.1 The "nothing" content model 3.2.5.2 Kinds of content 3.2.5.2.1 Metadata content 3.2.5.2.2 Flow content 3.2.5.2.3 Sectioning content 3.2.5.2.4 Heading content 3.2.5.2.5 Phrasing content 3.2.5.2.6 Embedded content 3.2.5.2.7 Interactive content 3.2.5.2.8 Palpable content 3.2.5.2.9 Script-supporting elements 3.2.5.3 Transparent content models 3.2.5.4 Paragraphs 3.2.6 Global attributes 3.2.6.1 The title attribute 3.2.6.2 The lang and xml:lang attributes 3.2.6.3 The translate attribute 3.2.6.4 The dir attribute 3.2.6.5 The style attribute 3.2.6.6 Embedding custom non-visible data with the data-* attributes 3.2.7 The innerText and outerText properties 3.2.8 Requirements relating to the bidirectional algorithm 3.2.8.1 Authoring conformance criteria for bidirectional-algorithm formatting characters 3.2.8.2 User agent conformance criteria 3.2.9 Requirements related to ARIA and to platform accessibility APIs 4 The elements of HTML 4.1 The document element 4.1.1 The html element 4.2 Document metadata 4.2.1 The head element 4.2.2 The title element 4.2.3 The base element 4.2.4 The link element 4.2.4.1 Processing the media attribute 4.2.4.2 Processing the type attribute 4.2.4.3 Fetching and processing a resource from a link element 4.2.4.4 Processing
13.2.10.3 Unexpected markup in tables 13.2.10.4 Scripts that modify the page as it is being parsed 13.2.10.5 The execution of scripts that are moving across multiple documents 13.2.10.6 Unclosed formatting elements 13.3 Serializing HTML fragments 13.4 Parsing HTML fragments 13.5 Named character references 14 The XML syntax 14.1 Writing documents in the XML syntax 14.2 Parsing XML documents 14.3 Serializing XML fragments 14.4 Parsing XML fragments 15 Rendering 15.1 Introduction 15.2 The CSS user agent style sheet and presentational hints 15.3 Non-replaced elements 15.3.1 Hidden elements 15.3.2 The page 15.3.3 Flow content 15.3.4 Phrasing content 15.3.5 Bidirectional text 15.3.6 Sections and headings 15.3.7 Lists 15.3.8 Tables 15.3.9 Margin collapsing quirks 15.3.10 Form controls 15.3.11 The hr element 15.3.12 The fieldset and legend elements 15.4 Replaced elements 15.4.1 Embedded content 15.4.2 Images 15.4.3 Attributes for embedded content and images 15.4.4 Image maps 15.5 Widgets 15.5.1 Native appearance 15.5.2 Writing mode 15.5.3 Button layout 15.5.4 The button element 15.5.5 The details and summary elements 15.5.6 The input element as a text entry widget 15.5.7 The input element as domain-specific widgets 15.5.8 The input element as a range control 15.5.9 The input element as a color well 15.5.10 The input element as a checkbox and radio button widgets 15.5.11 The input element as a file upload control 15.5.12 The input element as a button 15.5.13 The marquee element 15.5.14 The meter element 15.5.15 The progress element 15.5.16 The select element 15.5.17 The textarea element 15.6 Frames and framesets 15.7 Interactive media 15.7.1 Links, forms, and navigation 15.7.2 The title attribute 15.7.3 Editing hosts 15.7.4 Text rendered in native user interfaces 15.8 Print media 15.9 Unstyled XML documents 16 Obsolete features 16.1 Obsolete but conforming features 16.1.1 Warnings for obsolete but conforming features 16.2 Non-conforming features 16.3 Requirements for implementations 16.3.1 The marquee element 16.3.2 Frames 16.3.3 Other elements, attributes and APIs 17 IANA considerations 17.1 text/html 17.2 multipart/x-mixed-replace 17.3 application/xhtml+xml 17.4 text/ping 17.5 application/microdata+json 17.6 text/event-stream 17.7 web+ scheme prefix Index Elements Element content categories Attributes Element interfaces All interfaces Events HTTP headers MIME types References Acknowledgments Intellectual property rightsLinkheaders 4.2.4.5 Early hints 4.2.4.6 Providing users with a means to follow hyperlinks created using the link element 4.2.5 The meta element 4.2.5.1 Standard metadata names 4.2.5.2 Other metadata names 4.2.5.3 Pragma directives 4.2.5.4 Specifying the document's character encoding 4.2.6 The style element 4.2.7 Interactions of styling and scripting 4.3 Sections 4.3.1 The body element 4.3.2 The article element 4.3.3 The section element 4.3.4 The nav element 4.3.5 The aside element 4.3.6 The h1, h2, h3, h4, h5, and h6 elements 4.3.7 The hgroup element 4.3.8 The header element 4.3.9 The footer element 4.3.10 The address element 4.3.11 Headings and outlines 4.3.11.1 Sample outlines 4.3.11.2 Exposing outlines to users 4.3.12 Usage summary 4.3.12.1 Article or section? 4.4 Grouping content 4.4.1 The p element 4.4.2 The hr element 4.4.3 The pre element 4.4.4 The blockquote element 4.4.5 The ol element 4.4.6 The ul element 4.4.7 The menu element 4.4.8 The li element 4.4.9 The dl element 4.4.10 The dt element 4.4.11 The dd element 4.4.12 The figure element 4.4.13 The figcaption element 4.4.14 The main element 4.4.15 The search element 4.4.16 The div element 4.5 Text-level semantics 4.5.1 The a element 4.5.2 The em element 4.5.3 The strong element 4.5.4 The small element 4.5.5 The s element 4.5.6 The cite element 4.5.7 The q element 4.5.8 The dfn element 4.5.9 The abbr element 4.5.10 The ruby element 4.5.11 The rt element 4.5.12 The rp element 4.5.13 The data element 4.5.14 The time element 4.5.15 The code element 4.5.16 The var element 4.5.17 The samp element 4.5.18 The kbd element 4.5.19 The sub and sup elements 4.5.20 The i element 4.5.21 The b element 4.5.22 The u element 4.5.23 The mark element 4.5.24 The bdi element 4.5.25 The bdo element 4.5.26 The span element 4.5.27 The br element 4.5.28 The wbr element 4.5.29 Usage summary 4.6 Links 4.6.1 Introduction 4.6.2 Links created by a and area elements 4.6.3 API for a and area elements 4.6.4 Following hyperlinks 4.6.5 Downloading resources 4.6.6 Hyperlink auditing 4.6.6.1 ThePing-FromandPing-Toheaders 4.6.7 Link types 4.6.7.1 Link type "alternate" 4.6.7.2 Link type "author" 4.6.7.3 Link type "bookmark" 4.6.7.4 Link type "canonical" 4.6.7.5 Link type "dns-prefetch" 4.6.7.6 Link type "expect" 4.6.7.7 Link type "external" 4.6.7.8 Link type "help" 4.6.7.9 Link type "icon" 4.6.7.10 Link type "license" 4.6.7.11 Link type "manifest" 4.6.7.12 Link type "modulepreload" 4.6.7.13 Link type "nofollow" 4.6.7.14 Link type "noopener" 4.6.7.15 Link type "noreferrer" 4.6.7.16 Link type "opener" 4.6.7.17 Link type "pingback" 4.6.7.18 Link type "preconnect" 4.6.7.19 Link type "prefetch" 4.6.7.20 Link type "preload" 4.6.7.21 Link type "privacy-policy" 4.6.7.22 Link type "search" 4.6.7.23 Link type "stylesheet" 4.6.7.24 Link type "tag" 4.6.7.25 Link Type "terms-of-service" 4.6.7.26 Sequential link types 4.6.7.26.1 Link type "next" 4.6.7.26.2 Link type "prev" 4.6.7.27 Other link types 4.7 Edits 4.7.1 The ins element 4.7.2 The del element 4.7.3 Attributes common to ins and del elements 4.7.4 Edits and paragraphs 4.7.5 Edits and lists 4.7.6 Edits and tables 4.8 Embedded content 4.8.1 The picture element 4.8.2 The source element 4.8.3 The img element 4.8.4 Images 4.8.4.1 Introduction 4.8.4.1.1 Adaptive images 4.8.4.2 Attributes common to source, img, and link elements 4.8.4.2.1 Srcset attributes 4.8.4.2.2 Sizes attributes 4.8.4.3 Processing model 4.8.4.3.1 When to obtain images 4.8.4.3.2 Reacting to DOM mutations 4.8.4.3.3 The list of available images 4.8.4.3.4 Decoding images 4.8.4.3.5 Updating the image data 4.8.4.3.6 Preparing an image for presentation 4.8.4.3.7 Selecting an image source 4.8.4.3.8 Creating a source set from attributes 4.8.4.3.9 Updating the source set 4.8.4.3.10 Parsing a srcset attribute 4.8.4.3.11 Parsing a sizes attribute 4.8.4.3.12 Normalizing the source densities 4.8.4.3.13 Reacting to environment changes 4.8.4.4 Requirements for providing text to act as an alternative for images 4.8.4.4.1 General guidelines 4.8.4.4.2 A link or button containing nothing but the image 4.8.4.4.3 A phrase or paragraph with an alternative graphical representation: charts, diagrams, graphs, maps, illustrations 4.8.4.4.4 A short phrase or label with an alternative graphical representation: icons, logos 4.8.4.4.5 Text that has been rendered to a graphic for typographical effect 4.8.4.4.6 A graphical representation of some of the surrounding text 4.8.4.4.7 Ancillary images 4.8.4.4.8 A purely decorative image that doesn't add any information 4.8.4.4.9 A group of images that form a single larger picture with no links 4.8.4.4.10 A group of images that form a single larger picture with links 4.8.4.4.11 A key part of the content 4.8.4.4.12 An image not intended for the user 4.8.4.4.13 An image in an email or private document intended for a specific person who is known to be able to view images 4.8.4.4.14 Guidance for markup generators 4.8.4.4.15 Guidance for conformance checkers 4.8.5 The iframe element 4.8.6 The embed element 4.8.7 The object element 4.8.8 The video element 4.8.9 The audio element 4.8.10 The track element 4.8.11 Media elements 4.8.11.1 Error codes 4.8.11.2 Location of the media resource 4.8.11.3 MIME types 4.8.11.4 Network states 4.8.11.5 Loading the media resource 4.8.11.6 Offsets into the media resource 4.8.11.7 Ready states 4.8.11.8 Playing the media resource 4.8.11.9 Seeking 4.8.11.10 Media resources with multiple media tracks 4.8.11.10.1 AudioTrackList and VideoTrackList objects 4.8.11.10.2 Selecting specific audio and video tracks declaratively 4.8.11.11 Timed text tracks 4.8.11.11.1 Text track model 4.8.11.11.2 Sourcing in-band text tracks 4.8.11.11.3 Sourcing out-of-band text tracks 4.8.11.11.4 Guidelines for exposing cues in various formats as text track cues 4.8.11.11.5 Text track API 4.8.11.11.6 Event handlers for objects of the text track APIs 4.8.11.11.7 Best practices for metadata text tracks 4.8.11.12 Identifying a track kind through a URL 4.8.11.13 User interface 4.8.11.14 Time ranges 4.8.11.15 The TrackEvent interface 4.8.11.16 Events summary 4.8.11.17 Security and privacy considerations 4.8.11.18 Best practices for authors using media elements 4.8.11.19 Best practices for implementers of media elements 4.8.12 The map element 4.8.13 The area element 4.8.14 Image maps 4.8.14.1 Authoring 4.8.14.2 Processing model 4.8.15 MathML 4.8.16 SVG 4.8.17 Dimension attributes 4.9 Tabular data 4.9.1 The table element 4.9.1.1 Techniques for describing tables 4.9.1.2 Techniques for table design 4.9.2 The caption element 4.9.3 The colgroup element 4.9.4 The col element 4.9.5 The tbody element 4.9.6 The thead element 4.9.7 The tfoot element 4.9.8 The tr element 4.9.9 The td element 4.9.10 The th element 4.9.11 Attributes common to td and th elements 4.9.12 Processing model 4.9.12.1 Forming a table 4.9.12.2 Forming relationships between data cells and header cells 4.9.13 Examples 4.10 Forms 4.10.1 Introduction 4.10.1.1 Writing a form's user interface 4.10.1.2 Implementing the server-side processing for a form 4.10.1.3 Configuring a form to communicate with a server 4.10.1.4 Client-side form validation 4.10.1.5 Enabling client-side automatic filling of form controls 4.10.1.6 Improving the user experience on mobile devices 4.10.1.7 The difference between the field type, the autofill field name, and the input modality 4.10.1.8 Date, time, and number formats 4.10.2 Categories 4.10.3 The form element 4.10.4 The label element 4.10.5 The input element 4.10.5.1 States of the type attribute 4.10.5.1.1 Hidden state (type=hidden) 4.10.5.1.2 Text (type=text) state and Search state (type=search) 4.10.5.1.3 Telephone state (type=tel) 4.10.5.1.4 URL state (type=url) 4.10.5.1.5 Email state (type=email) 4.10.5.1.6 Password state (type=password) 4.10.5.1.7 Date state (type=date) 4.10.5.1.8 Month state (type=month) 4.10.5.1.9 Week state (type=week) 4.10.5.1.10 Time state (type=time) 4.10.5.1.11 Local Date and Time state (type=datetime-local) 4.10.5.1.12 Number state (type=number) 4.10.5.1.13 Range state (type=range) 4.10.5.1.14 Color state (type=color) 4.10.5.1.15 Checkbox state (type=checkbox) 4.10.5.1.16 Radio Button state (type=radio) 4.10.5.1.17 File Upload state (type=file) 4.10.5.1.18 Submit Button state (type=submit) 4.10.5.1.19 Image Button state (type=image) 4.10.5.1.20 Reset Button state (type=reset) 4.10.5.1.21 Button state (type=button) 4.10.5.2 Implementation notes regarding localization of form controls 4.10.5.3 Common input element attributes 4.10.5.3.1 The maxlength and minlength attributes 4.10.5.3.2 The size attribute 4.10.5.3.3 The readonly attribute 4.10.5.3.4 The required attribute 4.10.5.3.5 The multiple attribute 4.10.5.3.6 The pattern attribute 4.10.5.3.7 The min and max attributes 4.10.5.3.8 The step attribute 4.10.5.3.9 The list attribute 4.10.5.3.10 The placeholder attribute 4.10.5.4 Common input element APIs 4.10.5.5 Common event behaviors 4.10.6 The button element 4.10.7 The select element 4.10.8 The datalist element 4.10.9 The optgroup element 4.10.10 The option element 4.10.11 The textarea element 4.10.12 The output element 4.10.13 The progress element 4.10.14 The meter element 4.10.15 The fieldset element 4.10.16 The legend element 4.10.17 Form control infrastructure 4.10.17.1 A form control's value 4.10.17.2 Mutability 4.10.17.3 Association of controls and forms 4.10.18 Attributes common to form controls 4.10.18.1 Naming form controls: the name attribute 4.10.18.2 Submitting element directionality: the dirname attribute 4.10.18.3 Limiting user input length: the maxlength attribute 4.10.18.4 Setting minimum input length requirements: the minlength attribute 4.10.18.5 Enabling and disabling form controls: the disabled attribute 4.10.18.6 Form submission attributes 4.10.18.7 Autofill 4.10.18.7.1 Autofilling form controls: the autocomplete attribute 4.10.18.7.2 Processing model 4.10.19 APIs for the text control selections 4.10.20 Constraints 4.10.20.1 Definitions 4.10.20.2 Constraint validation 4.10.20.3 The constraint validation API 4.10.20.4 Security 4.10.21 Form submission 4.10.21.1 Introduction 4.10.21.2 Implicit submission 4.10.21.3 Form submission algorithm 4.10.21.4 Constructing the entry list 4.10.21.5 Selecting a form submission encoding 4.10.21.6 Converting an entry list to a list of name-value pairs 4.10.21.7 URL-encoded form data 4.10.21.8 Multipart form data 4.10.21.9 Plain text form data 4.10.21.10 The SubmitEvent interface 4.10.21.11 The FormDataEvent interface 4.10.22 Resetting a form 4.11 Interactive elements 4.11.1 The details element 4.11.2 The summary element 4.11.3 Commands 4.11.3.1 Facets 4.11.3.2 Using the a element to define a command 4.11.3.3 Using the button element to define a command 4.11.3.4 Using the input element to define a command 4.11.3.5 Using the option element to define a command 4.11.3.6 Using the accesskey attribute on a legend element to define a command 4.11.3.7 Using the accesskey attribute to define a command on other elements 4.11.4 The dialog element 4.12 Scripting 4.12.1 The script element 4.12.1.1 Processing model 4.12.1.2 Scripting languages 4.12.1.3 Restrictions for contents of script elements 4.12.1.4 Inline documentation for external scripts 4.12.1.5 Interaction of script elements and XSLT 4.12.2 The noscript element 4.12.3 The template element 4.12.3.1 Interaction of template elements with XSLT and XPath 4.12.4 The slot element 4.12.5 The canvas element 4.12.5.1 The 2D rendering context 4.12.5.1.1 Implementation notes 4.12.5.1.2 The canvas state 4.12.5.1.3 Line styles 4.12.5.1.4 Text styles 4.12.5.1.5 Building paths 4.12.5.1.6 Path2D objects 4.12.5.1.7 Transformations 4.12.5.1.8 Image sources for 2D rendering contexts 4.12.5.1.9 Fill and stroke styles 4.12.5.1.10 Drawing rectangles to the bitmap 4.12.5.1.11 Drawing text to the bitmap 4.12.5.1.12 Drawing paths to the canvas 4.12.5.1.13 Drawing focus rings 4.12.5.1.14 Drawing images 4.12.5.1.15 Pixel manipulation 4.12.5.1.16 Compositing 4.12.5.1.17 Image smoothing 4.12.5.1.18 Shadows 4.12.5.1.19 Filters 4.12.5.1.20 Working with externally-defined SVG filters 4.12.5.1.21 Drawing model 4.12.5.1.22 Best practices 4.12.5.1.23 Examples 4.12.5.2 The ImageBitmap rendering context 4.12.5.2.1 Introduction 4.12.5.2.2 The ImageBitmapRenderingContext interface 4.12.5.3 The OffscreenCanvas interface 4.12.5.3.1 The offscreen 2D rendering context 4.12.5.4 Color spaces and color space conversion 4.12.5.5 Serializing bitmaps to a file 4.12.5.6 Security with canvas elements 4.12.5.7 Premultiplied alpha and the 2D rendering context 4.13 Custom elements 4.13.1 Introduction 4.13.1.1 Creating an autonomous custom element 4.13.1.2 Creating a form-associated custom element 4.13.1.3 Creating a custom element with default accessible roles, states, and properties 4.13.1.4 Creating a customized built-in element 4.13.1.5 Drawbacks of autonomous custom elements 4.13.1.6 Upgrading elements after their creation 4.13.1.7 Exposing custom element states 4.13.2 Requirements for custom element constructors and reactions 4.13.3 Core concepts 4.13.4 The CustomElementRegistry interface 4.13.5 Upgrades 4.13.6 Custom element reactions 4.13.7 Element internals 4.13.7.1 The ElementInternals interface 4.13.7.2 Shadow root access 4.13.7.3 Form-associated custom elements 4.13.7.4 Accessibility semantics 4.13.7.5 Custom state pseudo-class 4.14 Common idioms without dedicated elements 4.14.1 Breadcrumb navigation 4.14.2 Tag clouds 4.14.3 Conversations 4.14.4 Footnotes 4.15 Disabled elements 4.16 Matching HTML elements using selectors and CSS 4.16.1 Case-sensitivity of the CSS 'attr()' function 4.16.2 Case-sensitivity of selectors 4.16.3 Pseudo-classes 5 Microdata 5.1 Introduction 5.1.1 Overview 5.1.2 The basic syntax 5.1.3 Typed items 5.1.4 Global identifiers for items 5.1.5 Selecting names when defining vocabularies 5.2 Encoding microdata 5.2.1 The microdata model 5.2.2 Items 5.2.3 Names: the itemprop attribute 5.2.4 Values 5.2.5 Associating names with items 5.2.6 Microdata and other namespaces 5.3 Sample microdata vocabularies 5.3.1 vCard 5.3.1.1 Conversion to vCard 5.3.1.2 Examples 5.3.2 vEvent 5.3.2.1 Conversion to iCalendar 5.3.2.2 Examples 5.3.3 Licensing works 5.3.3.1 Examples 5.4 Converting HTML to other formats 5.4.1 JSON 6 User interaction 6.1 The hidden attribute 6.2 Page visibility 6.2.1 The VisibilityStateEntry interface 6.3 Inert subtrees 6.3.1 Modal dialogs and inert subtrees 6.3.2 The inert attribute 6.4 Tracking user activation 6.4.1 Data model 6.4.2 Processing model 6.4.3 APIs gated by user activation 6.4.4 The UserActivation interface 6.4.5 User agent automation 6.5 Activation behavior of elements 6.5.1 The ToggleEvent interface 6.6 Focus 6.6.1 Introduction 6.6.2 Data model 6.6.3 The tabindex attribute 6.6.4 Processing model 6.6.5 Sequential focus navigation 6.6.6 Focus management APIs 6.6.7 The autofocus attribute 6.7 Assigning keyboard shortcuts 6.7.1 Introduction 6.7.2 The accesskey attribute 6.7.3 Processing model 6.8 Editing 6.8.1 Making document regions editable: The contenteditable content attribute 6.8.2 Making entire documents editable: the designMode getter and setter 6.8.3 Best practices for in-page editors 6.8.4 Editing APIs 6.8.5 Spelling and grammar checking 6.8.6 Writing suggestions 6.8.7 Autocapitalization 6.8.8 Input modalities: the inputmode attribute 6.8.9 Input modalities: the enterkeyhint attribute 6.9 Find-in-page 6.9.1 Introduction 6.9.2 Interaction with details and hidden=until-found 6.9.3 Interaction with selection 6.10 Close requests and close watchers 6.10.1 Close requests 6.10.2 Close watcher infrastructure 6.10.3 The CloseWatcher interface 6.11 Drag and drop 6.11.1 Introduction 6.11.2 The drag data store 6.11.3 The DataTransfer interface 6.11.3.1 The DataTransferItemList interface 6.11.3.2 The DataTransferItem interface 6.11.4 The DragEvent interface 6.11.5 Processing model 6.11.6 Events summary 6.11.7 The draggable attribute 6.11.8 Security risks in the drag-and-drop model 6.12 The popover attribute 6.12.1 The popover target attributes 6.12.2 Popover light dismiss 7 Loading web pages 7.1 Supporting concepts 7.1.1 Origins 7.1.1.1 Sites 7.1.1.2 Relaxing the same-origin restriction 7.1.2 Origin-keyed agent clusters 7.1.3 Cross-origin opener policies 7.1.3.1 The headers 7.1.3.2 Browsing context group switches due to cross-origin opener policy 7.1.3.3 Reporting 7.1.4 Cross-origin embedder policies 7.1.4.1 The headers 7.1.4.2 Embedder policy checks 7.1.5 Sandboxing 7.1.6 Policy containers 7.2 APIs related to navigation and session history 7.2.1 Security infrastructure for Window, WindowProxy, and Location objects 7.2.1.1 Integration with IDL 7.2.1.2 Shared internal slot: [[CrossOriginPropertyDescriptorMap]] 7.2.1.3 Shared abstract operations 7.2.1.3.1 CrossOriginProperties ( O ) 7.2.1.3.2 CrossOriginPropertyFallback ( P ) 7.2.1.3.3 IsPlatformObjectSameOrigin ( O ) 7.2.1.3.4 CrossOriginGetOwnPropertyHelper ( O, P ) 7.2.1.3.5 CrossOriginGet ( O, P, Receiver ) 7.2.1.3.6 CrossOriginSet ( O, P, V, Receiver ) 7.2.1.3.7 CrossOriginOwnPropertyKeys ( O ) 7.2.2 The Window object 7.2.2.1 Opening and closing windows 7.2.2.2 Indexed access on the Window object 7.2.2.3 Named access on the Window object 7.2.2.4 Accessing related windows 7.2.2.5 Historical browser interface element APIs 7.2.2.6 Script settings for Window objects 7.2.3 The WindowProxy exotic object 7.2.3.1 [[GetPrototypeOf]] ( ) 7.2.3.2 [[SetPrototypeOf]] ( V ) 7.2.3.3 [[IsExtensible]] ( ) 7.2.3.4 [[PreventExtensions]] ( ) 7.2.3.5 [[GetOwnProperty]] ( P ) 7.2.3.6 [[DefineOwnProperty]] ( P, Desc ) 7.2.3.7 [[Get]] ( P, Receiver ) 7.2.3.8 [[Set]] ( P, V, Receiver ) 7.2.3.9 [[Delete]] ( P ) 7.2.3.10 [[OwnPropertyKeys]] ( ) 7.2.4 The Location interface 7.2.4.1 [[GetPrototypeOf]] ( ) 7.2.4.2 [[SetPrototypeOf]] ( V ) 7.2.4.3 [[IsExtensible]] ( ) 7.2.4.4 [[PreventExtensions]] ( ) 7.2.4.5 [[GetOwnProperty]] ( P ) 7.2.4.6 [[DefineOwnProperty]] ( P, Desc ) 7.2.4.7 [[Get]] ( P, Receiver ) 7.2.4.8 [[Set]] ( P, V, Receiver ) 7.2.4.9 [[Delete]] ( P ) 7.2.4.10 [[OwnPropertyKeys]] ( ) 7.2.5 The History interface 7.2.6 The navigation API 7.2.6.1 Introduction 7.2.6.2 The Navigation interface 7.2.6.3 Core infrastructure 7.2.6.4 Initializing and updating the entry list 7.2.6.5 The NavigationHistoryEntry interface 7.2.6.6 The history entry list 7.2.6.7 Initiating navigations 7.2.6.8 Ongoing navigation tracking 7.2.6.9 The NavigationActivation interface 7.2.6.10 The navigate event 7.2.6.10.1 The NavigateEvent interface 7.2.6.10.2 The NavigationDestination interface 7.2.6.10.3 Firing the event 7.2.6.10.4 Scroll and focus behavior 7.2.7 Event interfaces 7.2.7.1 The NavigationCurrentEntryChangeEvent interface 7.2.7.2 The PopStateEvent interface 7.2.7.3 The HashChangeEvent interface 7.2.7.4 The PageSwapEvent interface 7.2.7.5 The PageRevealEvent interface 7.2.7.6 The PageTransitionEvent interface 7.2.7.7 The BeforeUnloadEvent interface 7.2.8 The NotRestoredReasons interface 7.3 Infrastructure for sequences of documents 7.3.1 Navigables 7.3.1.1 Traversable navigables 7.3.1.2 Top-level traversables 7.3.1.3 Child navigables 7.3.1.4 Jake diagrams 7.3.1.5 Related navigable collections 7.3.1.6 Navigable destruction 7.3.1.7 Navigable target names 7.3.2 Browsing contexts 7.3.2.1 Creating browsing contexts 7.3.2.2 Related browsing contexts 7.3.2.3 Groupings of browsing contexts 7.3.3 Fully active documents 7.4 Navigation and session history 7.4.1 Session history 7.4.1.1 Session history entries 7.4.1.2 Document state 7.4.1.3 Centralized modifications of session history 7.4.1.4 Low-level operations on session history 7.4.2 Navigation 7.4.2.1 Supporting concepts 7.4.2.2 Beginning navigation 7.4.2.3 Ending navigation 7.4.2.3.1 The usual cross-document navigation case 7.4.2.3.2 The javascript: URL special case 7.4.2.3.3 Fragment navigations 7.4.2.3.4 Non-fetch schemes and external software 7.4.2.4 Preventing navigation 7.4.2.5 Aborting navigation 7.4.3 Reloading and traversing 7.4.4 Non-fragment synchronous "navigations" 7.4.5 Populating a session history entry 7.4.6 Applying the history step 7.4.6.1 Updating the traversable 7.4.6.2 Updating the document 7.4.6.3 Revealing the document 7.4.6.4 Scrolling to a fragment 7.4.6.5 Persisted history entry state 7.5 Document lifecycle 7.5.1 Shared document creation infrastructure 7.5.2 Loading HTML documents 7.5.3 Loading XML documents 7.5.4 Loading text documents 7.5.5 Loading multipart/x-mixed-replace documents 7.5.6 Loading media documents 7.5.7 Loading a document for inline content that doesn't have a DOM 7.5.8 Finishing the loading process 7.5.9 Unloading documents 7.5.10 Destroying documents 7.5.11 Aborting a document load 7.6 TheX-Frame-Optionsheader 7.7 TheRefreshheader 7.8 Browser user interface considerations 8 Web application APIs 8.1 Scripting 8.1.1 Introduction 8.1.2 Agents and agent clusters 8.1.2.1 Integration with the JavaScript agent formalism 8.1.2.2 Integration with the JavaScript agent cluster formalism 8.1.3 Realms and their counterparts 8.1.3.1 Environments 8.1.3.2 Environment settings objects 8.1.3.3 Realms, settings objects, and global objects 8.1.3.3.1 Entry 8.1.3.3.2 Incumbent 8.1.3.3.3 Current 8.1.3.3.4 Relevant 8.1.3.4 Enabling and disabling scripting 8.1.3.5 Secure contexts 8.1.4 Script processing model 8.1.4.1 Scripts 8.1.4.2 Fetching scripts 8.1.4.3 Creating scripts 8.1.4.4 Calling scripts 8.1.4.5 Killing scripts 8.1.4.6 Runtime script errors 8.1.4.7 Unhandled promise rejections 8.1.4.8 Import map parse results 8.1.5 Module specifier resolution 8.1.5.1 The resolution algorithm 8.1.5.2 Import maps 8.1.5.3 Import map processing model 8.1.6 JavaScript specification host hooks 8.1.6.1 HostEnsureCanAddPrivateElement(O) 8.1.6.2 HostEnsureCanCompileStrings(realm, parameterStrings, bodyString, codeString, compilationType, parameterArgs, bodyArg) 8.1.6.3 HostGetCodeForEval(argument) 8.1.6.4 HostPromiseRejectionTracker(promise, operation) 8.1.6.5 HostSystemUTCEpochNanoseconds(global) 8.1.6.6 Job-related host hooks 8.1.6.6.1 HostCallJobCallback(callback, V, argumentsList) 8.1.6.6.2 HostEnqueueFinalizationRegistryCleanupJob(finalizationRegistry) 8.1.6.6.3 HostEnqueueGenericJob(job, realm) 8.1.6.6.4 HostEnqueuePromiseJob(job, realm) 8.1.6.6.5 HostEnqueueTimeoutJob(job, realm, milliseconds) 8.1.6.6.6 HostMakeJobCallback(callable) 8.1.6.7 Module-related host hooks 8.1.6.7.1 HostGetImportMetaProperties(moduleRecord) 8.1.6.7.2 HostGetSupportedImportAttributes() 8.1.6.7.3 HostLoadImportedModule(referrer, moduleRequest, loadState, payload) 8.1.7 Event loops 8.1.7.1 Definitions 8.1.7.2 Queuing tasks 8.1.7.3 Processing model 8.1.7.4 Generic task sources 8.1.7.5 Dealing with the event loop from other specifications 8.1.8 Events 8.1.8.1 Event handlers 8.1.8.2 Event handlers on elements, Document objects, and Window objects 8.1.8.2.1 IDL definitions 8.1.8.3 Event firing 8.2 The WindowOrWorkerGlobalScope mixin 8.3 Base64 utility methods 8.4 Dynamic markup insertion 8.4.1 Opening the input stream 8.4.2 Closing the input stream 8.4.3 document.write() 8.4.4 document.writeln() 8.5 DOM parsing and serialization APIs 8.5.1 The DOMParser interface 8.5.2 Unsafe HTML parsing methods 8.5.3 HTML serialization methods 8.5.4 The innerHTML property 8.5.5 The outerHTML property 8.5.6 The insertAdjacentHTML() method 8.5.7 The createContextualFragment() method 8.6 Timers 8.7 Microtask queuing 8.8 User prompts 8.8.1 Simple dialogs 8.8.2 Printing 8.9 System state and capabilities 8.9.1 The Navigator object 8.9.1.1 Client identification 8.9.1.2 Language preferences 8.9.1.3 Browser state 8.9.1.4 Custom scheme handlers: the registerProtocolHandler() method 8.9.1.4.1 Security and privacy 8.9.1.4.2 User agent automation 8.9.1.5 Cookies 8.9.1.6 PDF viewing support 8.10 Images 8.11 Animation frames 9 Communication 9.1 The MessageEvent interface 9.2 Server-sent events 9.2.1 Introduction 9.2.2 The EventSource interface 9.2.3 Processing model 9.2.4 TheLast-Event-IDheader 9.2.5 Parsing an event stream 9.2.6 Interpreting an event stream 9.2.7 Authoring notes 9.2.8 Connectionless push and other features 9.2.9 Garbage collection 9.2.10 Implementation advice 9.3 Cross-document messaging 9.3.1 Introduction 9.3.2 Security 9.3.2.1 Authors 9.3.2.2 User agents 9.3.3 Posting messages 9.4 Channel messaging 9.4.1 Introduction 9.4.1.1 Examples 9.4.1.2 Ports as the basis of an object-capability model on the web 9.4.1.3 Ports as the basis of abstracting out service implementations 9.4.2 Message channels 9.4.3 Message ports 9.4.4 Ports and garbage collection 9.5 Broadcasting to other browsing contexts 10 Web workers 10.1 Introduction 10.1.1 Scope 10.1.2 Examples 10.1.2.1 A background number-crunching worker 10.1.2.2 Using a JavaScript module as a worker 10.1.2.3 Shared workers introduction 10.1.2.4 Shared state using a shared worker 10.1.2.5 Delegation 10.1.2.6 Providing libraries 10.1.3 Tutorials 10.1.3.1 Creating a dedicated worker 10.1.3.2 Communicating with a dedicated worker 10.1.3.3 Shared workers 10.2 Infrastructure 10.2.1 The global scope 10.2.1.1 The WorkerGlobalScope common interface 10.2.1.2 Dedicated workers and the DedicatedWorkerGlobalScope interface 10.2.1.3 Shared workers and the SharedWorkerGlobalScope interface 10.2.2 The event loop 10.2.3 The worker's lifetime 10.2.4 Processing model 10.2.5 Runtime script errors 10.2.6 Creating workers 10.2.6.1 The AbstractWorker mixin 10.2.6.2 Script settings for workers 10.2.6.3 Dedicated workers and the Worker interface 10.2.6.4 Shared workers and the SharedWorker interface 10.2.7 Concurrent hardware capabilities 10.3 APIs available to workers 10.3.1 Importing scripts and libraries 10.3.2 The WorkerNavigator interface 10.3.3 The WorkerLocation interface 11 Worklets 11.1 Introduction 11.1.1 Motivations 11.1.2 Code idempotence 11.1.3 Speculative evaluation 11.2 Examples 11.2.1 Loading scripts 11.2.2 Registering a class and invoking its methods 11.3 Infrastructure 11.3.1 The global scope 11.3.1.1 Agents and event loops 11.3.1.2 Creation and termination 11.3.1.3 Script settings for worklets 11.3.2 The Worklet class 11.3.3 The worklet's lifetime 12 Web storage 12.1 Introduction 12.2 The API 12.2.1 The Storage interface 12.2.2 The sessionStorage getter 12.2.3 The localStorage getter 12.2.4 The StorageEvent interface 12.3 Privacy 12.3.1 User tracking 12.3.2 Sensitivity of data 12.4 Security 12.4.1 DNS spoofing attacks 12.4.2 Cross-directory attacks 12.4.3 Implementation risks 13 The HTML syntax 13.1 Writing HTML documents 13.1.1 The DOCTYPE 13.1.2 Elements 13.1.2.1 Start tags 13.1.2.2 End tags 13.1.2.3 Attributes 13.1.2.4 Optional tags 13.1.2.5 Restrictions on content models 13.1.2.6 Restrictions on the contents of raw text and escapable raw text elements 13.1.3 Text 13.1.3.1 Newlines 13.1.4 Character references 13.1.5 CDATA sections 13.1.6 Comments 13.2 Parsing HTML documents 13.2.1 Overview of the parsing model 13.2.2 Parse errors 13.2.3 The input byte stream 13.2.3.1 Parsing with a known character encoding 13.2.3.2 Determining the character encoding 13.2.3.3 Character encodings 13.2.3.4 Changing the encoding while parsing 13.2.3.5 Preprocessing the input stream 13.2.4 Parse state 13.2.4.1 The insertion mode 13.2.4.2 The stack of open elements 13.2.4.3 The list of active formatting elements 13.2.4.4 The element pointers 13.2.4.5 Other parsing state flags 13.2.5 Tokenization 13.2.5.1 Data state 13.2.5.2 RCDATA state 13.2.5.3 RAWTEXT state 13.2.5.4 Script data state 13.2.5.5 PLAINTEXT state 13.2.5.6 Tag open state 13.2.5.7 End tag open state 13.2.5.8 Tag name state 13.2.5.9 RCDATA less-than sign state 13.2.5.10 RCDATA end tag open state 13.2.5.11 RCDATA end tag name state 13.2.5.12 RAWTEXT less-than sign state 13.2.5.13 RAWTEXT end tag open state 13.2.5.14 RAWTEXT end tag name state 13.2.5.15 Script data less-than sign state 13.2.5.16 Script data end tag open state 13.2.5.17 Script data end tag name state 13.2.5.18 Script data escape start state 13.2.5.19 Script data escape start dash state 13.2.5.20 Script data escaped state 13.2.5.21 Script data escaped dash state 13.2.5.22 Script data escaped dash dash state 13.2.5.23 Script data escaped less-than sign state 13.2.5.24 Script data escaped end tag open state 13.2.5.25 Script data escaped end tag name state 13.2.5.26 Script data double escape start state 13.2.5.27 Script data double escaped state 13.2.5.28 Script data double escaped dash state 13.2.5.29 Script data double escaped dash dash state 13.2.5.30 Script data double escaped less-than sign state 13.2.5.31 Script data double escape end state 13.2.5.32 Before attribute name state 13.2.5.33 Attribute name state 13.2.5.34 After attribute name state 13.2.5.35 Before attribute value state 13.2.5.36 Attribute value (double-quoted) state 13.2.5.37 Attribute value (single-quoted) state 13.2.5.38 Attribute value (unquoted) state 13.2.5.39 After attribute value (quoted) state 13.2.5.40 Self-closing start tag state 13.2.5.41 Bogus comment state 13.2.5.42 Markup declaration open state 13.2.5.43 Comment start state 13.2.5.44 Comment start dash state 13.2.5.45 Comment state 13.2.5.46 Comment less-than sign state 13.2.5.47 Comment less-than sign bang state 13.2.5.48 Comment less-than sign bang dash state 13.2.5.49 Comment less-than sign bang dash dash state 13.2.5.50 Comment end dash state 13.2.5.51 Comment end state 13.2.5.52 Comment end bang state 13.2.5.53 DOCTYPE state 13.2.5.54 Before DOCTYPE name state 13.2.5.55 DOCTYPE name state 13.2.5.56 After DOCTYPE name state 13.2.5.57 After DOCTYPE public keyword state 13.2.5.58 Before DOCTYPE public identifier state 13.2.5.59 DOCTYPE public identifier (double-quoted) state 13.2.5.60 DOCTYPE public identifier (single-quoted) state 13.2.5.61 After DOCTYPE public identifier state 13.2.5.62 Between DOCTYPE public and system identifiers state 13.2.5.63 After DOCTYPE system keyword state 13.2.5.64 Before DOCTYPE system identifier state 13.2.5.65 DOCTYPE system identifier (double-quoted) state 13.2.5.66 DOCTYPE system identifier (single-quoted) state 13.2.5.67 After DOCTYPE system identifier state 13.2.5.68 Bogus DOCTYPE state 13.2.5.69 CDATA section state 13.2.5.70 CDATA section bracket state 13.2.5.71 CDATA section end state 13.2.5.72 Character reference state 13.2.5.73 Named character reference state 13.2.5.74 Ambiguous ampersand state 13.2.5.75 Numeric character reference state 13.2.5.76 Hexadecimal character reference start state 13.2.5.77 Decimal character reference start state 13.2.5.78 Hexadecimal character reference state 13.2.5.79 Decimal character reference state 13.2.5.80 Numeric character reference end state 13.2.6 Tree construction 13.2.6.1 Creating and inserting nodes 13.2.6.2 Parsing elements that contain only text 13.2.6.3 Closing elements that have implied end tags 13.2.6.4 The rules for parsing tokens in HTML content 13.2.6.4.1 The "initial" insertion mode 13.2.6.4.2 The "before html" insertion mode 13.2.6.4.3 The "before head" insertion mode 13.2.6.4.4 The "in head" insertion mode 13.2.6.4.5 The "in head noscript" insertion mode 13.2.6.4.6 The "after head" insertion mode 13.2.6.4.7 The "in body" insertion mode 13.2.6.4.8 The "text" insertion mode 13.2.6.4.9 The "in table" insertion mode 13.2.6.4.10 The "in table text" insertion mode 13.2.6.4.11 The "in caption" insertion mode 13.2.6.4.12 The "in column group" insertion mode 13.2.6.4.13 The "in table body" insertion mode 13.2.6.4.14 The "in row" insertion mode 13.2.6.4.15 The "in cell" insertion mode 13.2.6.4.16 The "in select" insertion mode 13.2.6.4.17 The "in select in table" insertion mode 13.2.6.4.18 The "in template" insertion mode 13.2.6.4.19 The "after body" insertion mode 13.2.6.4.20 The "in frameset" insertion mode 13.2.6.4.21 The "after frameset" insertion mode 13.2.6.4.22 The "after after body" insertion mode 13.2.6.4.23 The "after after frameset" insertion mode 13.2.6.5 The rules for parsing tokens in foreign content 13.2.7 The end 13.2.8 Speculative HTML parsing 13.2.9 Coercing an HTML DOM into an infoset 13.2.10 An introduction to error handling and strange cases in the parser 13.2.10.1 Misnested tags: 13.2.10.2 Misnested tags: