Reactjs 无法读取null的属性“value”?
尝试使用此.username.value时出错。我想获取要在标签中显示的文本框的值。我是个反应新手。如何使用InputRef从文本框获取变量值并显示在标签中Reactjs 无法读取null的属性“value”?,reactjs,react-redux,Reactjs,React Redux,尝试使用此.username.value时出错。我想获取要在标签中显示的文本框的值。我是个反应新手。如何使用InputRef从文本框获取变量值并显示在标签中 import React from 'react'; import PropTypes from 'prop-types'; import { connect } from 'react-redux'; import Helmet from 'react-helmet'; import { createStructuredSelector
import React from 'react';
import PropTypes from 'prop-types';
import { connect } from 'react-redux';
import Helmet from 'react-helmet';
import { createStructuredSelector } from 'reselect';
import TextBox from 'components/Atoms/TextBox';
import makeSelectTestPage from './selectors';
export class TestPage extends React.PureComponent {
constructor(props) {
super(props);
this.username ='',
this.handelChange = this.handelChange.bind(this);
}
handelChange() {
console.log("Log",this.username.value);
<label> this.username.value</label>
}
render() {
return (
<div>
<Helmet
title="TestPage"
meta={[
{ name: 'description', content: 'Description of TestPage' },
]}
/>
<TextBox labelName="Input Vaue" placeholder="Test" ref={(inputRef) => { this.username = inputRef; }} defaultValue="Text" ></TextBox>
<button onClick={this.handelChange}>Login</button>
</div>
);
}
}
TestPage.propTypes = {
dispatch: PropTypes.func.isRequired,
};
const mapStateToProps = createStructuredSelector({
TestPage: makeSelectTestPage(),
});
function mapDispatchToProps(dispatch) {
return {
dispatch,
};
}
export default connect(mapStateToProps, mapDispatchToProps)(TestPage);
你的问题有几个错误。尝试理解下一段代码,您将能够将其应用于示例: 类测试扩展了React.Component{ 构造器{ 超级作物; this.state={ 值:, 用户名: } } 手电筒{ this.setState{value:e.target.value} } 手舔{ this.setState{username:this.state.value} } 渲染{ 回来 {this.state.username} 登录 } } ReactDOM.render,document.getElementById'container';