react常用hooks

useMount

const useMount = (callback) => {
  React.useEffect(callback, [])
}

useUnmounted

 1 const useUnmount = (callback) => {
 2   const callbackRef = React.useRef(callback)
 3   
 4   callbackRef.current = callback
 5   
 6   React.useEffect(() => {
 7     return () => {
 8       callbackRef.current()
 9     }
10   }, [])
11 }

定时器

 1 import React, {useState, useEffect} from "react"
 2 
 3 const Counter = ({initialCount = 0}) => {
 4   const [count, setCount] = useState(initialCount)
 5 
 6   useEffect(() => {
 7     const timerId = setInterval(() => {
 8       setCount(prevCount => prevCount + 1)
 9     }, 1000)
10 
11     return () => clearInterval(timerId);
12   }, [])
13 
14   return (
15     <div>
16       <h1>当前计数：{count}</h1>
17     </div>
18   )
19 }
20 
21 export default Counter

部分更新state

 1 import React, {useState, useEffect} from "react"
 2 
 3 const useSetState = (initState) => {
 4   const [state, setState] = React.useState(initState)
 5 
 6   const setMergeState = (value) => {
 7     setState((prevValue) => {
 8       const newValue = typeof value === 'function' ? value(prevValue) : value
 9       return newValue ? {...prevValue, ...newValue} : prevValue
10     })
11   }
12 
13   return [state, setMergeState]
14 }
15 
16 const Counter = ({initialCount = 0}) => {
17   const [person, setPerson] = useSetState({
18     name: 'aaaa',
19     age: 100
20   })
21   const onSetName = () => {
22     setPerson({name: 'bbb'})
23   }
24 
25   return (
26     <div>
27       <button onClick={onSetName}>改变</button>
28       <div>{person.name}</div>
29     </div>
30   )
31 }
32 
33 export default Counter