《前端面试题》- React - 如何区分函数组件和类组件

问题

如何区分函数组件和类组件？

答案

可以使用instanceof 或者Component.prototype.isReactComponent。

示例

函数组件

export default function FunctionComonent() {
    if(FunctionComonent.prototype.isReactComponent){
        console.log('FunctionComonent是类组件')
    }else{
        console.log('FunctionComonent函数式组件')
    }

    return <div>这是函数组件</div>
}

类组件

import React from 'react';

export default class ClassComponent extends React.Component {
    constructor(props) {
        super();
        if(ClassComponent.prototype.isReactComponent){
            console.log('ClassComponent 是类组件')
        }else{
            console.log('ClassComponent函数式组件')
        }
    }
    render() { return (<div>这是一个Class组件</div>) }
}

引用

import React from 'react';
import ReactDOM from 'react-dom';
import ClassComponent from './compareFunctionComponentAndClassComponent/ClassComponent.jsx';
import FunctionComponent from './compareFunctionComponentAndClassComponent/FunctionComponent';

const clas = new ClassComponent();
console.log(`ClassComponent is Class  ${clas instanceof React.Component}`);

const func = new FunctionComponent();
console.log(`FunctionComponent is Class  ${func instanceof React.Component}`);

ReactDOM.render(
  <React.StrictMode>
    <ClassComponent />
    <FunctionComponent />
  </React.StrictMode>,
  document.getElementById('root')
);

结果