我很难弄清楚如何将event.target.value
传递到下面的setState中。
我以为第一个事件(= event =
(会在闭包中传递并可用于返回,但是当我调试它时,我没有得到定义。
去event.target.value
?
class InputElement1CC extends React.Component {
state = {
inputText: "",
historyList: []
};
handleChange = event => {
this.setState(previousState => {
return {
inputText: event.target.value,
historyList: [...previousState.historyList, event.target.value]
};
});
};
render() {
return (
<div>
<a href="/">home</a>
<h1>InputElement1CC - Class Component</h1>
<input placeholder="Enter Some Text" onChange={this.handleChange} />
<br />
{this.state.inputText}
<hr />
<br />
<ul>
{this.state.historyList.map(rec => {
return <div>{rec}</div>;
})}
</ul>
</div>
);
}
}
export default InputElement1CC;
将值设置为变量并使用该变量。 像这样:
handleChange = event => {
const value = event.target.value;
this.setState(
state => ({
inputText: value,
historyList: [...state.historyList, value]
}),
() => console.log("state", this.state)
);
};