Question

在普通的旧javascript中我有DIV

<div class="movie" id="my_movie">

以及以下javascript代码

var myMovie = document.getElementById('my_movie');
myMovie.addEventListener('nv-enter', function (event) {
     console.log('change scope');
});

现在我在这个组件中有一个React组件，在render方法中，我正在返回我的div。如何为自定义事件添加事件侦听器？（我将此库用于电视应用 - https://github.com/ahiipsa/navigation）

import React, { Component } from 'react';

class MovieItem extends Component {

  render() {

    if(this.props.index === 0) {
      return (
        <div aria-nv-el aria-nv-el-current className="menu_item nv-default">
            <div className="indicator selected"></div>
            <div className="category">
                <span className="title">{this.props.movieItem.caption.toUpperCase()}</span>
            </div>
        </div>
      );
    }
    else {
      return (
        <div aria-nv-el className="menu_item nv-default">
            <div className="indicator selected"></div>
            <div className="category">
                <span className="title">{this.props.movieItem.caption.toUpperCase()}</span>
            </div>
        </div>
      );
    }
  }

}

export default MovieItem;

更新＃1：

我应用了答案中提供的所有想法。我将导航库设置为调试模式，我只能基于键盘导航我的菜单项（正如您在屏幕截图中看到的那样我可以导航到电影4）但是当我将一个项目聚焦在菜单中时按回车键，我在控制台中看不到任何内容。

import React, { Component } from 'react';
import ReactDOM from 'react-dom';

class MenuItem extends Component {

  constructor(props) {
    super(props);
    // Pre-bind your event handler, or define it as a fat arrow in ES7/TS
    this.handleNVFocus = this.handleNVFocus.bind(this);
    this.handleNVEnter = this.handleNVEnter.bind(this);
    this.handleNVRight = this.handleNVRight.bind(this);
  }

  handleNVFocus = event => {
      console.log('Focused: ' + this.props.menuItem.caption.toUpperCase());
  }

  handleNVEnter = event => {
      console.log('Enter: ' + this.props.menuItem.caption.toUpperCase());
  }

  handleNVRight = event => {
      console.log('Right: ' + this.props.menuItem.caption.toUpperCase());
  }

  componentDidMount() {
    ReactDOM.findDOMNode(this).addEventListener('nv-focus', this.handleNVFocus);
    ReactDOM.findDOMNode(this).addEventListener('nv-enter', this.handleNVEnter);
    ReactDOM.findDOMNode(this).addEventListener('nv-right', this.handleNVEnter);
    //this.refs.nv.addEventListener('nv-focus', this.handleNVFocus);
    //this.refs.nv.addEventListener('nv-enter', this.handleNVEnter);
    //this.refs.nv.addEventListener('nv-right', this.handleNVEnter);
  }

  componentWillUnmount() {
    ReactDOM.findDOMNode(this).removeEventListener('nv-focus', this.handleNVFocus);
    ReactDOM.findDOMNode(this).removeEventListener('nv-enter', this.handleNVEnter);
    ReactDOM.findDOMNode(this).removeEventListener('nv-right', this.handleNVRight);
    //this.refs.nv.removeEventListener('nv-focus', this.handleNVFocus);
    //this.refs.nv.removeEventListener('nv-enter', this.handleNVEnter);
    //this.refs.nv.removeEventListener('nv-right', this.handleNVEnter);
  }

  render() {
    var attrs = this.props.index === 0 ? {"aria-nv-el-current": true} : {};
    return (
      <div ref="nv" aria-nv-el {...attrs} className="menu_item nv-default">
          <div className="indicator selected"></div>
          <div className="category">
              <span className="title">{this.props.menuItem.caption.toUpperCase()}</span>
          </div>
      </div>
    )
  }

}

export default MenuItem;

我留下了一些注释，因为在这两种情况下我都无法记录控制台线。

更新＃2：此导航库与React及其原始Html标签不兼容，因此我必须设置选项并重命名标签以使用aria- *，这样它就不会影响React。

navigation.setOption('prefix','aria-nv-el');
navigation.setOption('attrScope','aria-nv-scope');
navigation.setOption('attrScopeFOV','aria-nv-scope-fov');
navigation.setOption('attrScopeCurrent','aria-nv-scope-current');
navigation.setOption('attrElement','aria-nv-el');
navigation.setOption('attrElementFOV','aria-nv-el-fov');
navigation.setOption('attrElementCurrent','aria-nv-el-current');

Answer 1

如果需要handle DOM events not already provided by React，则必须在安装组件后添加DOM侦听器：

更新： 在React 13,14和15之间对API进行了更改，以影响我的回答。以下是使用React 15和ES7的最新方法。有关旧版本，请参阅answer history。

class MovieItem extends React.Component {

  componentDidMount() {
    // When the component is mounted, add your DOM listener to the "nv" elem.
    // (The "nv" elem is assigned in the render function.)
    this.nv.addEventListener("nv-enter", this.handleNvEnter);
  }

  componentWillUnmount() {
    // Make sure to remove the DOM listener when the component is unmounted.
    this.nv.removeEventListener("nv-enter", this.handleNvEnter);
  }

  // Use a class arrow function (ES7) for the handler. In ES6 you could bind()
  // a handler in the constructor.
  handleNvEnter = (event) => {
    console.log("Nv Enter:", event);
  }

  render() {
    // Here we render a single <div> and toggle the "aria-nv-el-current" attribute
    // using the attribute spread operator. This way only a single <div>
    // is ever mounted and we don't have to worry about adding/removing
    // a DOM listener every time the current index changes. The attrs 
    // are "spread" onto the <div> in the render function: {...attrs}
    const attrs = this.props.index === 0 ? {"aria-nv-el-current": true} : {};

    // Finally, render the div using a "ref" callback which assigns the mounted 
    // elem to a class property "nv" used to add the DOM listener to.
    return (
      <div ref={elem => this.nv = elem} aria-nv-el {...attrs} className="menu_item nv-default">
        ...
      </div>
    );
  }

}

Example on Codepen.io

Answer 2

您可以使用componentDidMount和componentWillUnmount方法：

import React, { Component } from 'react';
import ReactDOM from 'react-dom';

class MovieItem extends Component
{
    _handleNVEvent = event => {
        ...
    };

    componentDidMount() {
        ReactDOM.findDOMNode(this).addEventListener('nv-event', this._handleNVEvent);
    }

    componentWillUnmount() {
        ReactDOM.findDOMNode(this).removeEventListener('nv-event', this._handleNVEvent);
    }

    [...]

}

export default MovieItem;

Answer 3

我建议使用 React.createRef() 和 ref=this.elementRef 来获取 DOM 元素引用而不是 ReactDOM.findDOMNode(this)。通过这种方式，您可以获得对 DOM 元素的引用作为实例变量。

import React, { Component } from 'react';
import ReactDOM from 'react-dom';

class MenuItem extends Component {

  constructor(props) {
    super(props);

    this.elementRef = React.createRef();
  }

  handleNVFocus = event => {
      console.log('Focused: ' + this.props.menuItem.caption.toUpperCase());
  }
    
  componentDidMount() {
    this.elementRef.addEventListener('nv-focus', this.handleNVFocus);
  }

  componentWillUnmount() {
    this.elementRef.removeEventListener('nv-focus', this.handleNVFocus);
  }

  render() {
    return (
      <element ref={this.elementRef} />
    )
  }

}

export default MenuItem;

Answer 4

首先，自定义事件本身不能与React组件很好地配合使用。所以你不能在渲染函数中说<div onMyCustomEvent={something}>，并且必须考虑问题。

其次，在查看了您正在使用的库的文档之后，事件实际上是在document.body上触发的，所以即使它确实有效，您的事件处理程序也永远不会触发。

相反，在应用程序某处的componentDidMount内，您可以通过添加

来收听nv-enter

document.body.addEventListener('nv-enter', function (event) {
    // logic
});

然后，在回调函数中，点击一个改变组件状态的函数，或者你想做的任何事情。

ReactJS - 向组件添加自定义事件侦听器

4 个答案: