因为对我来说！ref.current.contains（e.target）无法工作，因为ref中包含的DOM元素正在更改，我提出了一个稍微不同的解决方案：

function useClickOutside<T extends HTMLElement>(
  element: T | null,
  onClickOutside: () => void,
) {
  useEffect(() => {
    function handleClickOutside(event: MouseEvent) {
      const xCoord = event.clientX;
      const yCoord = event.clientY;

      if (element) {
        const { right, x, bottom, y } = element.getBoundingClientRect();
        if (xCoord < right && xCoord > x && yCoord < bottom && yCoord > y) {
          return;
        }

        onClickOutside();
      }
    }

    document.addEventListener('click', handleClickOutside);
    return () => {
      document.removeEventListener('click', handleClickOutside);
    };
  }, [element, onClickOutside]);

import { RefObject, useEffect } from 'react';

const useClickOutside = <T extends HTMLElement>(ref: RefObject<T>, fn: () => void) => {
    useEffect(() => {
        const element = ref?.current;
        function handleClickOutside(event: Event) {
            if (element && !element.contains(event.target as Node | null)) {
                fn();
            }
        }
        document.addEventListener('mousedown', handleClickOutside);
        return () => {
            document.removeEventListener('mousedown', handleClickOutside);
        };
    }, [ref]);
};

export default useClickOutside;

2021更新：

自从我添加这个响应以来，已经有一段时间了，而且由于它似乎仍然引起了一些兴趣，我想我会将它更新到更新的React版本。2021，我会这样写这个组件：

import React, { useState } from "react";
import "./DropDown.css";

export function DropDown({ options, callback }) {
    const [selected, setSelected] = useState("");
    const [expanded, setExpanded] = useState(false);

    function expand() {
        setExpanded(true);
    }

    function close() {
        setExpanded(false);
    }

    function select(event) {
        const value = event.target.textContent;
        callback(value);
        close();
        setSelected(value);
    }

    return (
        <div className="dropdown" tabIndex={0} onFocus={expand} onBlur={close} >
            <div>{selected}</div>
            {expanded ? (
                <div className={"dropdown-options-list"}>
                    {options.map((O) => (
                        <div className={"dropdown-option"} onClick={select}>
                            {O}
                        </div>
                    ))}
                </div>
            ) : null}
        </div>
    );
}

原始答案（2016）：

以下是最适合我的解决方案，无需将事件附加到容器：

某些HTML元素可以具有所谓的“焦点”，例如输入元素。当这些元素失去焦点时，它们也会对模糊事件做出响应。

要使任何元素具有焦点的能力，只需确保其tabindex属性设置为-1以外的任何值。在常规HTML中，这是通过设置tabindex属性实现的，但在React中，必须使用tabindex（注意大写I）。

您也可以通过JavaScript使用element.setAttribute（'tabindex'，0）执行此操作

这就是我用来制作自定义下拉菜单的原因。

var DropDownMenu = React.createClass({
    getInitialState: function(){
        return {
            expanded: false
        }
    },
    expand: function(){
        this.setState({expanded: true});
    },
    collapse: function(){
        this.setState({expanded: false});
    },
    render: function(){
        if(this.state.expanded){
            var dropdown = ...; //the dropdown content
        } else {
            var dropdown = undefined;
        }
        
        return (
            <div className="dropDownMenu" tabIndex="0" onBlur={ this.collapse } >
                <div className="currentValue" onClick={this.expand}>
                    {this.props.displayValue}
                </div>
                {dropdown}
            </div>
        );
    }
});

这是我的方法（演示-https://jsfiddle.net/agymay93/4/):

我创建了一个名为WatchClickOutside的特殊组件，它可以像这样使用（我假设JSX语法）：

<WatchClickOutside onClickOutside={this.handleClose}>
  <SomeDropdownEtc>
</WatchClickOutside>

以下是WatchClickOutside组件的代码：

import React, { Component } from 'react';

export default class WatchClickOutside extends Component {
  constructor(props) {
    super(props);
    this.handleClick = this.handleClick.bind(this);
  }

  componentWillMount() {
    document.body.addEventListener('click', this.handleClick);
  }

  componentWillUnmount() {
    // remember to remove all events to avoid memory leaks
    document.body.removeEventListener('click', this.handleClick);
  }

  handleClick(event) {
    const {container} = this.refs; // get container that we'll wait to be clicked outside
    const {onClickOutside} = this.props; // get click outside callback
    const {target} = event; // get direct click event target

    // if there is no proper callback - no point of checking
    if (typeof onClickOutside !== 'function') {
      return;
    }

    // if target is container - container was not clicked outside
    // if container contains clicked target - click was not outside of it
    if (target !== container && !container.contains(target)) {
      onClickOutside(event); // clicked outside - fire callback
    }
  }

  render() {
    return (
      <div ref="container">
        {this.props.children}
      </div>
    );
  }
}

我为所有场合制定了解决方案。

你应该使用一个高阶组件来包装你想要监听的组件。

这个组件示例只有一个属性：“onClickedOutside”，它接收函数。

ClickedOutside.js

import React, { Component } from "react";

export default class ClickedOutside extends Component {
  componentDidMount() {
    document.addEventListener("mousedown", this.handleClickOutside);
  }

  componentWillUnmount() {
    document.removeEventListener("mousedown", this.handleClickOutside);
  }

  handleClickOutside = event => {
    // IF exists the Ref of the wrapped component AND his dom children doesnt have the clicked component 
    if (this.wrapperRef && !this.wrapperRef.contains(event.target)) {
      // A props callback for the ClikedClickedOutside
      this.props.onClickedOutside();
    }
  };

  render() {
    // In this piece of code I'm trying to get to the first not functional component
    // Because it wouldn't work if use a functional component (like <Fade/> from react-reveal)
    let firstNotFunctionalComponent = this.props.children;
    while (typeof firstNotFunctionalComponent.type === "function") {
      firstNotFunctionalComponent = firstNotFunctionalComponent.props.children;
    }

    // Here I'm cloning the element because I have to pass a new prop, the "reference" 
    const children = React.cloneElement(firstNotFunctionalComponent, {
      ref: node => {
        this.wrapperRef = node;
      },
      // Keeping all the old props with the new element
      ...firstNotFunctionalComponent.props
    });

    return <React.Fragment>{children}</React.Fragment>;
  }
}

import React, { useState, useEffect, useRef } from "react";

const YourComponent: React.FC<ComponentProps> = (props) => {
  const ref = useRef<HTMLDivElement | null>(null);
  const [myState, setMyState] = useState(false);
  useEffect(() => {
    const listener = (event: MouseEvent) => {
      // we have to add some logic to decide whether or not a click event is inside of this editor
      // if user clicks on inside the div we dont want to setState
      // we add ref to div to figure out whether or not a user is clicking inside this div to determine whether or not event.target is inside the div
      if (
        ref.current &&
        event.target &&
        // contains is expect other: Node | null
        ref.current.contains(event.target as Node)
      ) {
        return;
      }
      // if we are outside
      setMyState(false);
    };
    // anytime user clics anywhere on the dom, that click event will bubble up into our body element
    // without { capture: true } it might not work
    document.addEventListener("click", listener, { capture: true });
    return () => {
      document.removeEventListener("click", listener, { capture: true });
    };
  }, []);

  return (
    <div  ref={ref}>
      ....
    </div>
  );
};