一个列表项而不是所有列表项的ReactJS悬停/鼠标悬停效果

Question

我是React的新手，所以这看起来似乎很简单，或者可能不是，我不确定。我正在建立一个基本的待办事项清单。我希望列表项上的鼠标悬停效果弹出“删除此”文本。但是到目前为止，对于我的代码，当我将鼠标悬停在列表项上时，所有列表项（而不只是一个）都会弹出“删除此”。

当我尝试通过为单个列表项创建新组件来解决此问题时，这似乎不起作用。任何帮助深表感谢！

class ToDosContainer extends React.Component {
  constructor(props) {
    super(props)

    this.state = {
      heading: 'Something You Need To Do?',
      todos: [
        'wake up',
        'brush your teeth'
      ],
    }

    this.addToDo = this.addToDo.bind(this)
  }

  addToDo(todo) {
    this.setState((state) => ({
      todos: state.todos.concat([todo])
    }))
  }
  render() {
    return (
      <div>
        <h1>To Do List</h1>
        <h3>{this.state.heading}</h3>
        <AddToDo addNew={this.addToDo} />
        <ShowList tasks={this.state.todos} />
      </div>  
    )
  }
}

class AddToDo extends React.Component {
  constructor(props) {
    super(props)

    this.state = {
      newToDo: ''
    }

    this.updateNewToDo = this.updateNewToDo.bind(this)
    this.handleAddToDo = this.handleAddToDo.bind(this)

  }

  //I think I can delete this part
  updateNewToDo(e) {
    this.setState({
      newToDo: e.target.value
    })
  }
 //

  handleAddToDo() {
    this.props.addNew(this.state.newToDo)
    this.setState({
      newToDo: ''
    })
  }

  render() {
    return (
      <div>
        <input
          type="text"
          value={this.state.newToDo}
          onChange={this.updateNewToDo}
         />
        <button onClick={this.handleAddToDo}> Add To Do </button>
      </div>
    )
  }
}

class ShowList extends React.Component {

  constructor(props) {
    super(props)

    this.state = {
      newToDo: ''
    }
  }

  onMouseOver(e) { 
    this.setState({
      text: 'delete me'
    })
    console.log('hey')
  }

  onMouseOut(e) { 
     this.setState({
      text: ''
    })
     console.log('hey hey')

  }

  render() {
   const { text } = this.state;
   return (
    <div>
       <h4>To Do's</h4>
       <ul>
          {this.props.tasks.map((todo) => {
            return <li onMouseEnter={this.onMouseOver.bind(this)} onMouseLeave={this.onMouseOut.bind(this)}> {todo} {text}</li>
          })}
       </ul>
    </div>
   ) 
  }
}

ReactDOM.render(<ToDosContainer />, document.getElementById('helloworld')); 

Answer 1

我将创建一个Task组件。您不想设置组件中文本的状态ListView，因为这this.state.text将由地图中的每个任务共享。每个任务应该知道自己的悬停，而不是其他孩子的悬停。

class Task extends React.Component {
  state = {
    text: ""
  };
  onMouseOver(e) {
    this.setState({
      text: "delete me"
    });
  }

  onMouseOut(e) {
    this.setState({
      text: ""
    });
  }

  render() {
    return (
      <li
        onMouseEnter={this.onMouseOver.bind(this)}
        onMouseLeave={this.onMouseOut.bind(this)}
      >
        {this.props.todo} {this.state.text}
      </li>
    );
  }
}


class ShowList extends React.Component {
  constructor(props) {
    super(props);

    this.state = {
      newToDo: ""
    };
  }

  render() {
    const { text } = this.state;
    return (
      <div>
        <h4>To Do's</h4>
        <ul>
          {this.props.tasks.map(todo => {
            return <Task todo={todo} />;
          })}
        </ul>
      </div>
    );
  }
}