ReactJS如何从列表中删除项目 [英] ReactJS how to delete item from list
问题描述
我有代码可以创建< li>
元素。我需要通过单击逐个删除元素。对于每个元素,我有删除按钮
。我知道我需要一些函数来删除 id
项目。如何使用此函数删除ReactJS中的元素?
我的代码:
I have have code that creates <li>
elements. I need to delete elements one by one by clicking. For each element I have Delete button
. I understand that I need some function to delete items by id
. How to do this function to delete elements in ReactJS?
My code:
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>
);
}
}
推荐答案
你管理Parent组件中的数据并在Child组件中呈现UI,因此要从子组件中删除项目,您需要将函数与数据一起传递,从子组件调用该函数并传递列表项的任何唯一标识符,在父组件中删除使用该唯一标识符的项目。
You are managing the data in Parent component and rendering the UI in Child component, so to delete item from child component you need to pass a function along with data, call that function from child and pass any unique identifier of list item, inside parent component delete the item using that unique identifier.
Step1:从父组件传递函数以及数据,如下所示:
Step1: Pass a function from parent component along with data, like this:
<TodoList items={this.state.items} _handleDelete={this.delete.bind(this)}/>
第2步:定义删除
在父组件中的函数如下:
Step2: Define delete
function in parent component like this:
delete(id){
this.setState(prevState => ({
data: prevState.data.filter(el => el != id )
}));
}
步骤3:使用子组件调用该函数 this.props._handleDelete()
:
Step3: Call that function from child component using this.props._handleDelete()
:
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>
);
}
}
检查此工作示例:
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'/>
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