TypeError: instance.render is not a function-蒲公英云

TypeError: instance.render is not a function

1、错误描述

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2、错误原因

import React, {Component} from 'react';
import {render} from 'react-dom';
import Button from 'react-bootstrap/Button'
class InputRead extends Component {
    constructor() {
        return { user: '' };
    }
    inputChange(e) {
        this.setState({user:e.target.value});
    }
    clearAndFocus() {
        this.setState({user:''},()=>{
            this.refs.thisInput.focus();
        })
    }
    render() {
        return (
            <div>
                <Button onClick={this.clearAndFocus.bind(this)}>
                    清空
                </Button>
                <input ref="thisInput" value={this.state.user} onChange={this.inputChange.bind(this)}/>
            </div>
        )
    }
}
export default InputRead;

构造函数中不能使用return语句，否则以为构造函数中需要添加render()方法

3、解决办法

import React, {Component} from 'react';
import {render} from 'react-dom';
import Button from 'react-bootstrap/Button'
class InputRead extends Component {
    constructor(props) {
        //return { user: '' };
        super(props);
        this.state = { user: '' };
    }
    inputChange(e) {
        this.setState({user:e.target.value});
    }
    clearAndFocus() {
        this.setState({user:''},()=>{
            this.refs.thisInput.focus();
        })
    }
    render() {
        return (
            <div>
                <Button onClick={this.clearAndFocus.bind(this)}>
                    清空
                </Button>
                <input ref="thisInput" value={this.state.user} onChange={this.inputChange.bind(this)}/>
            </div>
        )
    }
}
export default InputRead;