1.6 KiB
1.6 KiB
title | localeTitle |
---|---|
Use Array.map() to Dynamically Render Elements | 使用Array.map()动态渲染元素 |
使用Array.map()动态渲染元素
提示1:
将两个状态定义为JavaScript object
。
{object: state, object: state}
提示2:
您需要.map()
为数组中的每个对象生成一行。
this.state.toDoList.map(i => <li>{i}</li>);
解:
添加地图功能后,您会注意到它会为您放入列表中的每个项目生成<li>
。
const textAreaStyles = {
width: 235,
margin: 5
};
class MyToDoList extends React.Component {
constructor(props) {
super(props);
// change code below this line
this.state = {
userInput: '',
toDoList: []
}
// change code above this line
this.handleSubmit = this.handleSubmit.bind(this);
this.handleChange = this.handleChange.bind(this);
}
handleSubmit() {
const itemsArray = this.state.userInput.split(',');
this.setState({
toDoList: itemsArray
});
}
handleChange(e) {
this.setState({
userInput: e.target.value
});
}
render() {
const items = this.state.toDoList.map(i => <li>{i}</li>); // change code here
return (
<div>
<textarea
onChange={this.handleChange}
value={this.state.userInput}
style={textAreaStyles}
placeholder="Separate Items With Commas" /><br />
<button onClick={this.handleSubmit}>Create List</button>
<h1>My "To Do" List:</h1>
<ul>
{items}
</ul>
</div>
);
}
};