ReactJS如何从列表中删除项目

Question

我有创建<li>元素的代码。我需要单击一次删除一个元素。对于每个元素，我都有Delete button。我了解我需要一些功能来通过删除项目id。如何使用此功能删除ReactJS中的元素？我的代码：

class TodoApp extends React.Component {
    constructor(props) {
        super(props);
        this.handleChange = this.handleChange.bind(this);
        this.handleSubmit = this.handleSubmit.bind(this);
        this.state = {items: [], text: ''};
    }

    render() {
        return (
            <div>
                <h3>TODO</h3>
                <TodoList items={this.state.items} />
                <form onSubmit={this.handleSubmit}>
                    <input onChange={this.handleChange} value={this.state.text} />
                    <button>{'Add #' + (this.state.items.length + 1)}</button>
                </form>
            </div>
        );
    }

    handleChange(e) {
        this.setState({text: e.target.value});
    }

    handleSubmit(e) {
        e.preventDefault();
        var newItem = {
            text: this.props.w +''+this.props.t,
            id: Date.now()
        };
        this.setState((prevState) => ({
            items: prevState.items.concat(newItem),
            text: ''
        }));
    }

    delete(id){          // How that function knows id of item that need to delete and how to delete item?
        this.setState(this.item.id)
    }
}

class TodoList extends React.Component {
    render() {
        return (
            <ul>
                {this.props.items.map(item => (
                    <li key={item.id}>{item.text}<button onClick={this.delete.bind(this)}>Delete</button></li>
                ))}
            </ul>
        );
    }
}

Answer 1

您正在父级组件中管理数据并在子级组件中呈现UI，因此要从子级组件中删除项目，您需要将一个函数与数据一起传递，从子级中调用该函数并在父级组件内部传递列表项的任何唯一标识符使用该唯一标识符删除项目。

步骤1： 将父组件的函数与数据一起传递，如下所示：

<TodoList items={this.state.items} _handleDelete={this.delete.bind(this)}/>

步骤2：delete在父组件中定义函数，如下所示：

delete(id){
    this.setState(prevState => ({
        data: prevState.data.filter(el => el != id )
    }));
}

第三步： 使用this.props._handleDelete()以下命令从子组件中调用该函数：

class TodoList extends React.Component {

    _handleDelete(id){
        this.props._handleDelete(id);
    }

    render() {
        return (
            <ul>
                {this.props.items.map(item => (
                    <li key={item.id}>{item.text}<button onClick={this._handleDelete.bind(this, item.id)}>Delete</button></li>
                ))}
            </ul>
        );
    }
}

检查以下工作示例：

class App extends React.Component{

   constructor(){

      super();

      this.state = {

        data: [1,2,3,4,5]

      }

      this.delete = this.delete.bind(this);

   }



   delete(id){

      this.setState(prevState => ({

          data: prevState.data.filter(el => el != id )

      }));

   }



   render(){

      return(

          <Child delete={this.delete} data={this.state.data}/>

      );

   }

}



class Child extends React.Component{



   delete(id){

       this.props.delete(id);

   }



   render(){

      return(

         <div>

           {

              this.props.data.map(el=>

                  <p onClick={this.delete.bind(this, el)}>{el}</p>

              )

           }

         </div>

      )

   }

}



ReactDOM.render(<App/>, document.getElementById('app'))


<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script>

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script>



<div id='app'/>