1.dom节点上使用,通过this.refs[refName]来引用真实的dom节点
<input ref="inputRef" /> //this.refs['inputRef']来访问
2.类组件上使用,通过this.refs[refName]来引用组件的实例
<CustomInput ref="comRef" /> //this.refs['comRef']来访问
2. 回调函数
回调函数就是在dom节点或组件上挂载函数,函数的入参是dom节点或组件实例,达到的效果与字符串形式是一样的,
都是获取其引用。
回调函数的触发时机:
1. 组件渲染后,即componentDidMount后
2. 组件卸载后,即componentWillMount后,此时,入参为null
3. ref改变后
1.dom节点上使用回调函数
<input ref={(input) => {this.textInput = input;}} type="text" />
2.类组件上使用
<CustomInput ref={(input) => {this.textInput = input;}} />
3.可用通过props跨级传递的方式来获取子孙级dom节点或组件实例
下面是在跨两级获取到孙级别的组件内部的dom节点
function CustomTextInput(props) {
return (
<input ref={props.inputRef} />
function Parent(props) {
return (
My input: <CustomTextInput inputRef={props.inputRef} />
class Grandparent extends React.Component {
render() {
return (
<Parent
inputRef={el => this.inputElement = el}
3.React.createRef()
在React 16.3版本后,使用此方法来创建ref。将其赋值给一个变量,通过ref挂载在dom节点或组件上,该ref的current属性
将能拿到dom节点或组件的实例
例如:
class Child extends React.Component{
constructor(props){
super(props);
this.myRef=React.createRef();
componentDidMount(){
console.log(this.myRef.current);
render(){
return <input ref={this.myRef}/>
4.React.forwardRef
同样是React 16.3版本后提供的,可以用来创建子组件,以传递ref。
例如:
//子组件(通过forwardRef方法创建)
const Child=React.forwardRef((props,ref)=>(
<input ref={ref} />
//父组件
class Father extends React.Component{
constructor(props){
super(props);
this.myRef=React.createRef();
componentDidMount(){
console.log(this.myRef.current);
render(){
return <Child ref={this.myRef}/>
子组件通过React.forwardRef来创建,可以将ref传递到内部的节点或组件,进而实现跨层级的引用。
forwardRef在高阶组件中可以获取到原始组件的实例。
//生成高阶组件
const logProps=logProps(Child);
//调用高阶组件
class Father extends React.Component{
constructor(props){
super(props);
this.myRef=React.createRef();
componentDidMount(){
console.log(this.myRef.current);
render(){
return <LogProps ref={this.myRef}/>
//HOC
function logProps(Component) {
class LogProps extends React.Component {
componentDidUpdate(prevProps) {
console.log('old props:', prevProps);
console.log('new props:', this.props);
render() {
const {forwardedRef, ...rest} = this.props;
// Assign the custom prop "forwardedRef" as a ref
return <Component ref={forwardedRef} {...rest} />;
// Note the second param "ref" provided by React.forwardRef.
// We can pass it along to LogProps as a regular prop, e.g. "forwardedRef"
// And it can then be attached to the Component.
return React.forwardRef((props, ref) => {
return <LogProps {...props} forwardedRef={ref} />;
//生成高阶组件
const logProps=logProps(Child);
//调用高阶组件
class Father extends React.Component{
constructor(props){
super(props);
this.myRef=React.createRef();
componentDidMount(){
console.log(this.myRef.current);
render(){
return <LogProps ref={this.myRef}/>
//HOC
function logProps(Component) {
class LogProps extends React.Component {
componentDidUpdate(prevProps) {
console.log('old props:', prevProps);
console.log('new props:', this.props);
render() {
const {forwardedRef, ...rest} = this.props;
// Assign the custom prop "forwardedRef" as a ref
return <Component ref={forwardedRef} {...rest} />;
// Note the second param "ref" provided by React.forwardRef.
// We can pass it along to LogProps as a regular prop, e.g. "forwardedRef"
// And it can then be attached to the Component.
return React.forwardRef((props, ref) => {
return <LogProps {...props} forwardedRef={ref} />;
注意:
1. ref在函数式组件上不可使用,函数式组件无实例,但是其内部的dom节点和类组件可以使用
2. 可以通过ReactDOM.findDOMNode(),入参是一个组件或dom节点,返回值的组件对应的dom根节点或dom节点本身
通过refs获取到组件实例后,可以通过此方法来获取其对应的dom节点
3. React的render函数返回的是vDom(虚拟dom)
参考:https://blog.csdn.net/liangklfang/article/details/72858295
https://blog.csdn.net/liwusen/article/details/80009968