最近react又有更新了，对于生命周期使用的更加严谨了 ，对于受控组件的好处 相比大家都知道 废话不多说，上代码~
import React, { Component } from 'react'
class Input extends Component {
constructor(props, context) {
super(props, context)
this.state = {
value: this.props.defaultValue || ''
}
this.changeHandler = this.changeHandler.bind(this)
}
get displayValue() {
const key = 'value'
const internalKey = 'value'
return this.props[key] !== undefined
? this.props[key]
: this.state[internalKey]
}
handleChange(newVal) {
if (newVal === this.state.value) {
return
}
this.setState(
{
value: newVal
},
() => {
this.props.onChange && this.props.onChange(this.props.name, newVal)
}
)
}
UNSAFE_componentWillReceiveProps(nextProps) {
const controlledValue = nextProps.defaultValue
if (controlledValue !== undefined && controlledValue !== this.state.value) {
this.setState(
{
value: controlledValue
},
() => {
this.props.onChange &&
this.props.onChange(nextProps.name, controlledValue)
}
)
}
}
shouldComponentUpdate(nextProps, nextState) {
if (nextProps.value !== undefined) {
return nextProps.value !== this.props.value
}
return nextState.value !== this.state.value
}
changeHandler(e) {
const val = e.target.value
this.handleChange(val)
}
render() {
return (
<input
className="editor"
placeholder={this.props.placeholder}
type={this.props.type}
name={this.props.name}
value={this.displayValue}
onChange={this.changeHandler}
/>
)
}
}
export default Input
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