π» Tiny Concurrent UI library with Fiber.
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Concurrent Mode β This is an amazing idea, which implements the coroutine scheduler in JavaScript, and the rendering is asynchronous with Time slicing.
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Offscreen rendering β Another idea which operate DOM in memory and paint them all to the screen at one time.
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Highly-optimized algorithm β Fre has a better reconciliation algorithm, It supported keyed, pre-process.
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Do more with less β After tree shaking, project of hello world is only 2KB, but it has most features, virtual DOM, hooks API, Fragment, Suspense and more.
yarn add fre
import { render, useState } from 'fre'
function App() {
const [count, setCount] = useState(0)
return <>
<h1>{count}</h1>
<button onClick={() => setCount(count + 1)}>+</button>
</>
}
createRoot(document.body).render(<App/>)
useState
is a base API, It will receive initial state and return an Array
You can use it many times, new state is available when component is rerender
function App() {
const [up, setUp] = useState(0)
const [down, setDown] = useState(0)
return (
<>
<h1>{up}</h1>
<button onClick={() => setUp(up + 1)}>+</button>
<h1>{down}</h1>
<button onClick={() => setDown(down - 1)}>-</button>
</>
)
}
useReducer
and useState
are almost the sameοΌbut useReducer
needs a global reducer
function reducer(state, action) {
switch (action.type) {
case 'up':
return { count: state.count + 1 }
case 'down':
return { count: state.count - 1 }
}
}
function App() {
const [state, dispatch] = useReducer(reducer, { count: 1 })
return (
<>
{state.count}
<button onClick={() => dispatch({ type: 'up' })}>+</button>
<button onClick={() => dispatch({ type: 'down' })}>-</button>
</>
)
}
It is the execution and cleanup of effects, which is represented by the second parameter
useEffect(f) // effect (and clean-up) every time
useEffect(f, []) // effect (and clean-up) only once in a component's life
useEffect(f, [x]) // effect (and clean-up) when property x changes in a component's life
function App({ flag }) {
const [count, setCount] = useState(0)
useEffect(() => {
document.title = 'count is ' + count
}, [flag])
return (
<>
<h1>{count}</h1>
<button onClick={() => setCount(count + 1)}>+</button>
</>
)
}
If it returns a function, the function can do cleanups:
useEffect(() => {
document.title = 'count is ' + count
return () => {
store.unsubscribe()
}
}, [])
More like useEffect, but useLayout is sync and blocking UI.
useLayout(() => {
document.title = 'count is ' + count
}, [flag])
useMemo
has the same rules as useEffect
, but useMemo
will return a cached value.
const memo = (c) => (props) => useMemo(() => c, [Object.values(props)])
useCallback
is based useMemo
, it will return a cached function.
const cb = useCallback(() => {
console.log('cb was cached.')
}, [])
useRef
will return a function or an object.
function App() {
useEffect(() => {
console.log(t) // { current:<div>t</div> }
})
const t = useRef(null)
return <div ref={t}>t</div>
}
If it uses a function, it can return a cleanup and executes when removed.
function App() {
const t = useRef((dom) => {
if (dom) {
doSomething()
} else {
cleanUp()
}
})
return flag && <span ref={t}>I will removed</span>
}
This is another feature of concurrent rendering, which can achieve asynchronous refresh without the aid of state.
const LazyComponent = lazy(Component)
function App() {
return <Suspense fallback={<div>Loading...</div>}>
<LazyComponent/>
</Suspense>
}
Similar to Suspense is ErrorBoundary, where rendering can fallback when errors are caught.
function App() {
return <ErrorBoundary fallback={(e)=>{
console.error(e)
return e
}}>
<ErrorComponent/>
</ErrorBoundary>
}
function ErrorComponent(){
throw 'err'
}
This is an unstable API and is not recommended until the last minute.
import {suspense, lazy, portal} from 'fre/mixins'
const root = createRoot(document.body)
root.mixin(suspense, lazy, portal)
root.render(<App/>)
Here is a mixin to disable time slicing:
export function enableTimeSlicing(fiber) {
fiber.sync = ture
return {
yield() {
if (fiber.sync === true) {
return false
}
},
capturing(fiber) {
console.log(fiber)
},
bubbling(fiber) {
console.log(fiber)
},
commit(fiber){
console.log(fiber)
}
}
}
plugins: [
[
'@babel/plugin-transform-react-jsx',
{
runtime: 'automatic',
importSource: 'fre',
},
],
]
The comparison is difficult because the roadmap and trade-offs of each framework are different, but we have to do so.
- react
React is the source of inspiration for fre. Their implementation and asynchronous rendering are similar. The most amazing thing is concurrent mode, which means that react and fre have the same roadmap -- Exploring concurrent use cases.
But at the same time, fre has obvious advantages in reconciliation algorithm and bundle size.
- vue / preact
To some extent, vue and preact are similar. They have similar synchronous rendering, only the API is different.
The reconciliation algorithm of fre is similar to vue, but the biggest difference is that vue/preact do not support concurrent mode, this means that the roadmap is totally different.
framework | concurrent | reconcilation algorithm | bundle size |
---|---|---|---|
fre2 | β | β β β β β | 2kb |
react18 | β | β β β | 43kb |
vue3 | Γ | β β β β β | 31kb |
preactX | Γ | β β β β | 4kb |
MIT @yisar