Reactjs 如何访问父组件中子组件的引用

建议用于16.3之前的React版本

如果无法避免，则从React docs中提取的建议模式为:

import React, { Component } from 'react';

const Child = ({ setRef }) => <input type="text" ref={setRef} />;

class Parent extends Component {
    constructor(props) {
        super(props);
        this.setRef = this.setRef.bind(this);
    }

    componentDidMount() {
        // Calling a function on the Child DOM element
        this.childRef.focus();
    }

    setRef(input) {
        this.childRef = input;
    }

    render() {
        return <Child setRef={this.setRef} />
    }
}

Parent将函数作为props 转发到Parent's this.当React调用Child's ref prop setRef时，它会将Child's ref分配给Parent's childRef属性.

建议用于react >=16.3

Ref-forwarding是一种 Select 性加入功能，允许一些组件获取他们接收到的Ref，并将其进一步向下传递(换句话说，"转发"给子组件).

我们创建了Components个，将其ref个和React.forwardRef个向前推进.

import React from "react";

const LibraryButton = React.forwardRef((props, ref) => (
  <button ref={ref} {...props}>
    FancyButton
  </button>
));

class AutoFocus extends React.Component {
  constructor(props) {
    super(props);
    this.childRef = React.createRef();
    this.onClick = this.onClick.bind(this);
  }

  componentDidMount() {
    this.childRef.current.focus();
  }

  onClick() {
    console.log("fancy!");
  }

  render() {
    return <LibraryButton onClick={this.onClick} ref={this.childRef} />;
  }
}

转发refs HOC示例

创建的Components正在将其ref转发到子 node .

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} />;
  });
}

见React docs中的Forwarding Refs.