React 输入和状态无法覆盖

Question

开始学习反应。我已经在这个问题上坐了一个小时，我不知道为什么这不起作用。到处寻找，但没有任何结果。我是笨蛋还是什么？

我无法在输入字段中写入，或者当我可以（如果我修复它）时，我的状态不会改变。也许有人知道为什么这是一个问题？

import './App.css';

class App extends Component {

  constructor(props) {

    super(props);

    this.state = {

      text: "test"

    }

  }

  textChangedHandler = (event) => {

    this.setState = ({

      text: event.target.value

    });

  } 

  render() {

    return (

      <div className="App">

        <p>{this.state.text}</p>

        <input 

          type="text"

          onChange={this.textChangedHandler}

          value={this.state.text}> 

        </input>

      </div>

    );

  }

}

export default App;

Answer 1

查看您的textChangedHandlertextChangedHandler = (event) => {&nbsp; &nbsp; this.setState = ({&nbsp; &nbsp; &nbsp; text: event.target.value&nbsp; &nbsp; });&nbsp; }&nbsp;在这种情况下，您需要像这样设置状态。this.setState({&nbsp; text: event.target.value})this.setState是一种方法。您应该需要重新分配它。

Answer 2

textChangedHandler = (event) => {&nbsp; &nbsp; this.setState({&nbsp; &nbsp; &nbsp; &nbsp; text: event.target.value&nbsp; &nbsp; });}render() {&nbsp; &nbsp; return (&nbsp; &nbsp; &nbsp; &nbsp; <div className="App">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; <p>{this.state.text}</p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; <input&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; type="text"&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; onChange={this.textChangedHandler}&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; value={this.state.text}>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; </input>&nbsp; &nbsp; &nbsp; &nbsp; </div>&nbsp; &nbsp; );}试试这个。

Answer 3

试试这个：import './App.css';class App extends Component {&nbsp; constructor(props) {&nbsp; &nbsp; super(props);&nbsp; &nbsp; this.state = {&nbsp; &nbsp; &nbsp; text: "test"&nbsp; &nbsp; }&nbsp; &nbsp; // This binding is necessary to make `this` work in the callback&nbsp; &nbsp; this.textChangedHandler = this.textChangedHandler.bind(this)&nbsp; }&nbsp; textChangedHandler = (event) => {&nbsp; &nbsp; this.setState({&nbsp; &nbsp; &nbsp; text: event.target.value&nbsp; &nbsp; });&nbsp; }&nbsp;&nbsp; render() {&nbsp; &nbsp; return (&nbsp; &nbsp; &nbsp; <div className="App">&nbsp; &nbsp; &nbsp; &nbsp; <p>{this.state.text}</p>&nbsp; &nbsp; &nbsp; &nbsp; <input&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; type="text"&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; onChange={this.textChangedHandler}&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; value={this.state.text}>&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; </input>&nbsp; &nbsp; &nbsp; </div>&nbsp; &nbsp; );&nbsp; }}export default App;更多信息： https://reactjs.org/docs/handling-events.html