A fiber is a JavaScript object, a unit of work. It represents a node of the DOM tree, or a React element, and contains data about a component, its I/P and O/P.
React Fiber is a backwards compatible, complete rewrite of the React core. In other words, it is a reimplementation of older versions of the React reconciler.
Introduced from React 16, Fiber Reconciler is the new reconciliation algorithm in React. The term Fiber refers to React's data structure (or) architecture, and originates from 'fiber' - a representation of a node of the DOM tree.
What is the purpose of React Fiber?
Improved performance
React Fiber is aimed at improving the perceived performance for complex React applications. It does so by allowing React to break the limits of the call stack. This lets it pause or start rendering work whenever required.
Better suitability for advanced UI
React Fiber also increases the suitability of the React library to create animations, layouts, and gestures.
Control over the "priority" of work
Through its feature of incremental rendering, React Fiber lets developers split rendering work into smaller chunks and distribute it over multiple frames. This allows users to essentially control the "priority" of work.
For example, React Fiber could help you prioritise functions that originate from user actions while delaying logic of less-important background or offscreen functions to avoid frame rate drops.
More fluid experience
So by breaking up the work into smaller chunks that can be paused, resumed, or aborted based on a set priority order, React Fiber helps apps deliver a more fluid experience. Fiber lets React fine-tune the rendering to ensure that the most common use-cases (or) the most important updates are computed at the earliest.Specifically, it helps improve the speed of rendering components at start-up, as they could be made available to the browser before the entire bundle finishes downloading.
How does React Fiber work?
To understand how React Fiber works, we must first understand what used to happen in React before Fiber.
React before React Fiber
React creates a tree of nodes when the UI renders for the very first time, with each node representing a React element. React creates a virtual tree (called virtualDOM), a clone of the rendered DOM tree.React then traverses the tree, updating the DOM on which classes or elements needed to be updated, whenever a change is required to be rendered. This is called Reconciliation.Essentially, after any UI update, React compares every node from two trees, and passes on the cumulative changes to the renderer.
But, before Fiber, reconciliation and rendering to the DOM weren't separated, and React couldn't pause its traversal to jump to other renders in between. This often resulted in lagging inputs and choppy frame rates.
In other words, with reconciliation forced to be without interruption (or "synchronous"), render changes couldn't be inserted in the middle. This prevented higher-priority changes from being made until the stack was completely cleared.
How does React Fiber work?
Fiber brings in different levels of priority for updates in React. It breaks the computation of the component tree into nodes, or 'units' of work that it can commit at any time. This allows React to pause, resume or restart computation for various components.
Fiber allows the reconciliation and rendering to the DOM to be split into two separate phases:
Phase 1: Reconciliation
In the first phase, React creates a list of all changes to be rendered in the UI (an 'effect list', comprising of new and updated components).Once the list is fully computed, React will schedule these changes to be executed in the next phase.Note that React doesn't make any actual changes in this phase.
Phase 2: Commit
In phase two, also called 'commit' phase, React tells the DOM to render the effect list that was created in the previous phase.While the Reconciliation phase can be interrupted, the Commit phase cannot.
So via Fiber, React is able to traverse the component tree through a singly linked list tree traversal algorithm. This algorithm can run in an "asynchronous" manner - allowing React to pause and resume work at particular nodes.
A fiber is a JavaScript object, a unit of work. It represents a node of the DOM tree, or a React element, and contains data about a component, its I/P and O/P.
React Fiber is a backwards compatible, complete rewrite of the React core. In other words, it is a reimplementation of older versions of the React reconciler.
Introduced from React 16, Fiber Reconciler is the new reconciliation algorithm in React. The term Fiber refers to React's data structure (or) architecture, and originates from 'fiber' - a representation of a node of the DOM tree.
What is the purpose of React Fiber?
Improved performance
React Fiber is aimed at improving the perceived performance for complex React applications. It does so by allowing React to break the limits of the call stack. This lets it pause or start rendering work whenever required. Better suitability for advanced UI
React Fiber also increases the suitability of the React library to create animations, layouts, and gestures. Control over the "priority" of work
Through its feature of incremental rendering, React Fiber lets developers split rendering work into smaller chunks and distribute it over multiple frames. This allows users to essentially control the "priority" of work. For example, React Fiber could help you prioritise functions that originate from user actions while delaying logic of less-important background or offscreen functions to avoid frame rate drops.
More fluid experience
So by breaking up the work into smaller chunks that can be paused, resumed, or aborted based on a set priority order, React Fiber helps apps deliver a more fluid experience. Fiber lets React fine-tune the rendering to ensure that the most common use-cases (or) the most important updates are computed at the earliest.Specifically, it helps improve the speed of rendering components at start-up, as they could be made available to the browser before the entire bundle finishes downloading.
How does React Fiber work? To understand how React Fiber works, we must first understand what used to happen in React before Fiber.
React before React Fiber React creates a tree of nodes when the UI renders for the very first time, with each node representing a React element. React creates a virtual tree (called virtualDOM), a clone of the rendered DOM tree.React then traverses the tree, updating the DOM on which classes or elements needed to be updated, whenever a change is required to be rendered. This is called Reconciliation.Essentially, after any UI update, React compares every node from two trees, and passes on the cumulative changes to the renderer. But, before Fiber, reconciliation and rendering to the DOM weren't separated, and React couldn't pause its traversal to jump to other renders in between. This often resulted in lagging inputs and choppy frame rates.
In other words, with reconciliation forced to be without interruption (or "synchronous"), render changes couldn't be inserted in the middle. This prevented higher-priority changes from being made until the stack was completely cleared.
How does React Fiber work? Fiber brings in different levels of priority for updates in React. It breaks the computation of the component tree into nodes, or 'units' of work that it can commit at any time. This allows React to pause, resume or restart computation for various components.
Fiber allows the reconciliation and rendering to the DOM to be split into two separate phases:
Phase 1: Reconciliation
In the first phase, React creates a list of all changes to be rendered in the UI (an 'effect list', comprising of new and updated components).Once the list is fully computed, React will schedule these changes to be executed in the next phase.Note that React doesn't make any actual changes in this phase. Phase 2: Commit
In phase two, also called 'commit' phase, React tells the DOM to render the effect list that was created in the previous phase.While the Reconciliation phase can be interrupted, the Commit phase cannot. So via Fiber, React is able to traverse the component tree through a singly linked list tree traversal algorithm. This algorithm can run in an "asynchronous" manner - allowing React to pause and resume work at particular nodes.