# React实现点击组件外部时触发事件

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I'm looking for a way to detect if a click event happened outside of a component, as described in this article. jQuery closest() is used to see if the target from a click event has the dom element as one of its parents. If there is a match the click event belongs to one of the children and is thus not considered to be outside of the component.

So in my component I want to attach a click handler to window. When the handler fires I need to compare the target with the dom children of my component.

The click event contains properties like "path" which seems to hold the dom path that the event has travelled. I'm not sure what to compare or how to best traverse it, and I'm thinking someone must have already put that in a clever utility function... No?

## 解决方法​

Refs usage in React 16.3+ changed.

The following solution uses ES6 and follows best practices for binding as well as setting the ref through a method.

To see it in action:

Hooks Implementation:

import React, { useRef, useEffect } from "react";/** * Hook that alerts clicks outside of the passed ref */function useOutsideAlerter(ref) {  useEffect(() => {    /**     * Alert if clicked on outside of element     */    function handleClickOutside(event) {      if (ref.current && !ref.current.contains(event.target)) {        alert("You clicked outside of me!");      }    }    // Bind the event listener    document.addEventListener("mousedown", handleClickOutside);    return () => {      // Unbind the event listener on clean up      document.removeEventListener("mousedown", handleClickOutside);    };  }, [ref]);}/** * Component that alerts if you click outside of it */export default function OutsideAlerter(props) {  const wrapperRef = useRef(null);  useOutsideAlerter(wrapperRef);  return <div ref={wrapperRef}>{props.children}</div>;}

Class Implementation:

import React, { Component } from "react";import PropTypes from "prop-types";/** * Component that alerts if you click outside of it */export default class OutsideAlerter extends Component {  constructor(props) {    super(props);    this.wrapperRef = React.createRef();    this.setWrapperRef = this.setWrapperRef.bind(this);    this.handleClickOutside = this.handleClickOutside.bind(this);  }  componentDidMount() {    document.addEventListener("mousedown", this.handleClickOutside);  }  componentWillUnmount() {    document.removeEventListener("mousedown", this.handleClickOutside);  }  /**   * Alert if clicked on outside of element   */  handleClickOutside(event) {    if (this.wrapperRef && !this.wrapperRef.current.contains(event.target)) {      alert("You clicked outside of me!");    }  }  render() {    return <div ref={this.wrapperRef}>{this.props.children}</div>;  }}OutsideAlerter.propTypes = {  children: PropTypes.element.isRequired,};