Using Proxy API to auto dispatch React.useState()
.
Inspired from @State()
in @stencil/core
.
## using npm
npm install use-state-proxy
## or using yarn
yarn add use-state-proxy
## or using pnpm
pnpm install use-state-proxy
type StateProxy<T extends object> = T
// auto trigger re-render when in-place update occurs
export function useStateProxy<T extends object>(initialValue: T): StateProxy<T>
// return the object reference to the initialValue
export function unProxy<T extends object>(proxy: StateProxy<T>): T
- Auto trigger re-render when invoking mutating methods on state fields
- Array
- Map
- Set
- Date
- Object
- Custom Classes
- Create a variant for shared state, as simpler alternative to redux store (using redux or context)
- Tested with
@testing-library/jest-dom
You can get/set the values, and call mutating methods (e.g. array.push()
) directly.
The 'setState' action is auto dispatched when the value is changed, which auto trigger re-rendering.
Usage Example:
import React from 'react'
import { useStateProxy } from 'use-state-proxy'
function DemoUseStateProxy() {
const state = useStateProxy({
text: '',
list: ['init'],
})
const { list } = state
return (
<>
<input value={state.text} onChange={e => (state.text = e.target.value)} />
<button
onClick={() => {
list.push(state.text)
state.text = ''
}}
>
Save
</button>
<ul>
{list.map((item, i) => (
<li key={i}>
<button onClick={() => list.splice(i, 1)}>Delete</button>
<span>{item}</span>
<input
value={item}
onChange={e => {
state.list[i] = e.target.value
state.list = state.list
}}
/>
</li>
))}
</ul>
</>
)
}
export default DemoUseStateProxy
Using useStateProxy()
, the array can be updated with state.list.push(state.text)
and state.list.splice(i, 1)
directly.
This invokes proxied methods, and it will auto trigger re-rendering.
You need to set up the states one-by-one, and explicitly call the setHooks to trigger re-rendering.
Moreover, there is syntax noise when updating complex data type, e.g. Array, Map, Set, and Object.
import React, { useState } from 'react'
function DemoUseState() {
const [text, setText] = useState('')
const [list, setList] = useState(['init'])
return (
<>
<input value={text} onChange={e => setText(e.target.value)} />
<button
onClick={() => {
setList([...list, text])
setText('')
}}
>
Save
</button>
<ul>
{list.map((item, i) => (
<li key={i}>
<button onClick={() => setList(list.filter((_, j) => i !== j))}>
Delete
</button>
<span>{item}</span>
<input
value={item}
onChange={e => {
const newList = [...list]
newList[i] = e.target.value
setList(newList)
}}
/>
</li>
))}
</ul>
</>
)
}
export default DemoUseState
In this example, in order to 'push' an item to the list, it manually destructs the original array with spread syntax ...
then append the new item at the end.
Also, to remove an item from the list, it constructs a new array with list.filter()
, involving multiple levels of array indices, which is error-prone.
The same hurdles applies to object as well, and it gets even worse when it comes to Set
* and Map
**.
*: To update a Set
, we can run setList(new Set([...list, item]))
or setList(new Set([...list].filter(x => x !== target)))
**: To update a Map
, we can run setList(new Map([...list, [key, value]]))
or setList(new Map([...list].filter(([key]) => key !== target)))
The mutating methods of custom classes can be registered. This mechanism allows use-state-proxy to auto trigger re-rendering even when the state consists of non-json values. (Array, Map, Set and Date are supported by default.)
Below demo how to register mutating methods on WeakSet with registerMutableMethodsByClassConstructor()
and registerMutableMethodsByClassName()
:
import {
registerMutableMethodsByClassConstructor,
registerMutableMethodsByClassName,
} from 'use-state-proxy'
let mutableWeakSetMethods: Array<keyof typeof WeakSet.prototype> = [
'add',
'delete',
]
registerMutableMethodsByClassConstructor(WeakSet, methods)
registerMutableMethodsByClassName('[object WeakSet]', methods) // to support cross-frame objects
You can also use helper functions getClassName()
and registerPrimitiveMutableClass()
to avoid typo mistakes.
import { getClassName, registerPrimitiveMutableClass } from 'use-state-proxy'
registerPrimitiveMutableClass(WeakSet, getClassName(new WeakSet()), [
'add',
'delete',
])
Details see demo-custom-mutable-class.ts
- Refactor into typical react-library structure https://medium.com/better-programming/build-your-very-own-react-component-library-and-publish-it-to-github-package-registry-192a688a51fd
BSD-2-Clause (Free Open Source Software)