snuggsi ツ - Easy Custom Elements in ~1kiloByte
All you need is a browser and basic understanding of HTML, CSS, & JavaScript classes to be productive!
Performance is the art of avoiding work
- #FreeJewelry 💍 💎
`itus](https://css-tricks.com/css-beginner-mistakes-1/), or need to install packages on a terminal just to write `HTML`. **People who are more comfortable with `HTML` should be able to start marking up their ideas immediately!** You shouldn't have to know CSS or JavaScript! _(But it definitely helps if you need styling and functionality)_.
**snuggsiツ** believes in using [Progressive Enhancement](https://en.wikipedia.org/wiki/Progressive_enhancement). Not just with your code, but also with your Developer eXperience _(DX)_. We will start from the beginning with a simple Custom Element and gradually enhance functionality step-by-step.
## [<`custom-elements`>](/element#readme)
When picking a name for your custom element [there are a few naming conventions](https://html.spec.whatwg.org/multipage/custom-elements.html#valid-custom-element-name) you must be aware of. We can simply use `hello-world` for now.
### `HTML` Declaration
`HTML` has always been a declarative language. Why not just use it to declare Custom Elements?
If you know [how to write `HTML`](https://developer.mozilla.org/en-US/docs/Web/HTML) you can start using **snuggsiツ**. Sometimes you need to sandbox a section of your page for styling. Other times you need a custom container of complex functionality. Either way you usually start with a plain ole' `HTML` element declaration:
#### A Brief History Lesson
_Not all HTML tags are created equal!_
A _"valid `HTML` Element"_ has always _allowed_ non-standard tag names _(as long as you remember to provide a closing tag)_. In the bad old days of the web, [`HTML5` elements were once _"non-standard"_ to `HTML 4.0`](https://johnresig.com/blog/html5-shiv):
```html
…
…
…
…
``` 👍 Rule of thumb: _Close all **non-standard** `HTML` Element tags!_
As you learned earlier there are a few conventions to adhere to be considered a _"valid **Custom** Element"_ you will need an alpha-numeric character followed by a hyphen in the tag name _(at minimum)_: ```html
We now know enough to be dangerous and make your own Custom Element tag: ```html
At this point your **custom** element can be styled using CSS just like any other element. ```html
Hello
```
See [A JavaScript-free custom element implementation](https://www.stefanjudis.com/notes/a-javascript-free-custom-element-implementation/)
And [Building a `` component](https://web.dev/building-a-tooltip-component/) for more _(sans JavaScript)_ custom elements CSS fun!
#### Live `{token}` Declarations The `{token}` is simply a [well named dynamic variable](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Grammar_and_types#Variables) you will **Describe** later. `{token}`s are placeholders which watch for changes to your custom element's `class` property of the same name. Since they are _"placeholders"_ and not live code, Front-end designers are no longer blocked by needing to install a JavaScript framework just to write `CSS`! ```html This is a token 👉 {baz} and {bat} is another!
```
👍 Rule of thumb: _If the `{token}` name is [not in a thesaurus](https://en.wikipedia.org/wiki/Metasyntactic_variable) then I probably shouldn't use it._
A _"live token"_ is a declarative way to bind data values to your Custom Element. A nice convention to a real historical P.I.T.A. of keeping values updated. Live `{token}`s are also _"✨ automagically"_ updated each time the element re-renders. Let's add a `{token}` to ``:
```html
Hello {planet}
```
👍 Rule of thumb: _A `{token}` is not _"live"_ until there is a `class` description for its functionality._
Lastly, we can visually enhance your `` Custom Element by making it [_"block level"_](https://developer.mozilla.org/en-US/docs/Web/HTML/Block-level_elements) with CSS `display: block`. This way your element plays nicely in your layout:
```html
Hello {planet}
```
We have finished your Custom Element **Declaration** using `HTML`, & `CSS`!🌟 Now on to your **Definition**.
### `Element` Definition Every Custom `Element` **MUST** be [_Defined_ within the `CustomElementsRegistry`](https://developer.mozilla.org/en-US/docs/Web/API/CustomElementRegistry). This is simple with **snuggsiツ** Let's `define` your element using the `Element` interface: ```javascript // …
Element `hello-world`
```
👍 Rule of thumb: _Use backticks around tag names (``)._
This syntax is not JSX. It's actually called [tagged template literals](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Template_literals#Tagged_templates) and is native to the platform.
Custom elements use the native `Element` interface definition strategy for two reasons:
1. To prevent you from worrying about browser inconsistencies as the technology matures.
2. Prevent global namespace pollution. _([`Element` has been native to the web platform for decades!](https://developer.mozilla.org/en-US/docs/Web/API/Element))_
Classic JavaScript syntax may also be used. However [this should be the job of a transpiler not the developer](https://en.wikipedia.org/wiki/Source-to-source_compiler).
Transpilers take care of [normalizing Modern JavaScript to a specific retrograde](https://developer.mozilla.org/en-US/docs/Learn/Tools_and_testing/Cross_browser_testing/JavaScript).
```javascript
Element ('hello-world') // classic javascript definition
```
### `class` Description Great so far!🎉 Although your Element behaves like any other `HTMLElement`, we should add some functionality custom to your needs. Next, we need to pass a `class` description to the function returned by your `Element` definition. ```javascript // …
Element `hello-world`
( class HelloWorld extends HTMLElement { … } )
```
👍 Rule of thumb: _**MUST** define [a `class` which `extends HTMLElement`](https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement)_
Let's shorten your description up a bit by using an [anonymous class expression](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/class) to describe the `class`. This convention is preferred as using an [explicit `class` declaration](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/class) name can potentially pollute the global namespace:
```javascript
// …
Element `hello-world`
( class extends HTMLElement { … } )
```
👍 Rule of thumb: _Use enclosing parenthesis around `(class …)` definitions._
#### Live `{token}` Definitions Since we [previously declared a `{planet}` token](#live-tokens) within your `` element we need to also define a `class property` **of the same name** to replace the `{planet}` token with a value.
Class properties may look like typical JavaScript Functions. However, they are treated as properties. _(called without parenthesis)_. `class` properties are described by using the [`get`ter](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/get) and [`set`ter](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/set) annotations before the name.
Let's add a property to your `class` definition and give `{planet}` some life:
```javascript
// … {planet} …
Element `hello-world`
(class extends HTMLElement {
get planet () // used for {planet} token
// "✨ automagic" token binding
{ return 'world 🌎' }
})
```
👍 Rule of thumb: _`class` properties are functions begining with the keywords `get` & `set`._
👍 Rule of thumb: _`{tokens}` will use the `class` property value of the same name by default._
⚠️ The Live `{token}` value is updated after each re-render but it beyond the scope of this simple example.
Since your `hello-world` Custom Element is an `HTMLElement` at its core, we can access your property directly from the DOM!
```javascript
// …
document.querySelector
('hello-world').planet // world 🌎
```
👍 Rule of thumb: _Do not use parenthesis `()` when calling `get`ters & `set`ters._
#### Global `event` Listeners `event` handlers can be any method function which can be placed on any child elements and also onto the custom element itself _(i.e.`onclick=eatBacon`)_. However, you will not have to explicitly set the handler in HTML when you follow native naming conventions. This is the magic behind **snuggsiツ** Global `event` Listeners. They register themselves onto the custom element and _"listen"_ for you! As a convenience, your new custom element uses [Event Delegation](https://developer.mozilla.org/en-US/docs/Learn/JavaScript/Building_blocks/Events#Event_delegation) to capture all its children's [event bubbles of the same name](https://javascript.info/bubbling-and-capturing). ```javascript //
// `onclick` is "automagically" attached
//
// ACHOO!
//
Element `hello-world`
(class extends HTMLElement {
// native event handler names
// are "✨automagically" attached to `hello-world`
onclick (event) {
// prevent event from bubbling
// Custom Element will re-render
// after event unless prevented
event.preventDefault ()
event.target // element which triggered event
this // is ALWAYS bound to the Custom Element container 🎉
}
onsneeze (event) {
/* must be declared in HTML
…
…
``` 👍 Rule of thumb: _Close all **non-standard** `HTML` Element tags!_
As you learned earlier there are a few conventions to adhere to be considered a _"valid **Custom** Element"_ you will need an alpha-numeric character followed by a hyphen in the tag name _(at minimum)_: ```html
We now know enough to be dangerous and make your own Custom Element tag: ```html
At this point your **custom** element can be styled using CSS just like any other element. ```html
#### Live `{token}` Declarations The `{token}` is simply a [well named dynamic variable](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Grammar_and_types#Variables) you will **Describe** later. `{token}`s are placeholders which watch for changes to your custom element's `class` property of the same name. Since they are _"placeholders"_ and not live code, Front-end designers are no longer blocked by needing to install a JavaScript framework just to write `CSS`! ```html
A _"live token"_ is a declarative way to bind data values to your Custom Element. A nice convention to a real historical P.I.T.A. of keeping values updated. Live `{token}`s are also _"✨ automagically"_ updated each time the element re-renders. Let's add a `{token}` to `
Lastly, we can visually enhance your `
### `Element` Definition Every Custom `Element` **MUST** be [_Defined_ within the `CustomElementsRegistry`](https://developer.mozilla.org/en-US/docs/Web/API/CustomElementRegistry). This is simple with **snuggsiツ** Let's `define` your element using the `Element` interface: ```javascript //
### `class` Description Great so far!🎉 Although your Element behaves like any other `HTMLElement`, we should add some functionality custom to your needs. Next, we need to pass a `class` description to the function returned by your `Element` definition. ```javascript //
#### Live `{token}` Definitions Since we [previously declared a `{planet}` token](#live-tokens) within your `
#### Global `event` Listeners `event` handlers can be any method function which can be placed on any child elements and also onto the custom element itself _(i.e.`onclick=eatBacon`)_. However, you will not have to explicitly set the handler in HTML when you follow native naming conventions. This is the magic behind **snuggsiツ** Global `event` Listeners. They register themselves onto the custom element and _"listen"_ for you! As a convenience, your new custom element uses [Event Delegation](https://developer.mozilla.org/en-US/docs/Learn/JavaScript/Building_blocks/Events#Event_delegation) to capture all its children's [event bubbles of the same name](https://javascript.info/bubbling-and-capturing). ```javascript //