react组件卸载前的钩子

参考：https://lequ7.com/2019/01/16/javascript/React-zu-jian-xie-zai-lu-you-tiao-zhuan-ye-mian-guan-bi-shua-xin-zhi-qian-jin-xing-ti-shi/

import {Prompt} from ‘react-router-dom’;
const Editor=()=>{
return (
    <div>
        <Prompt
            //  when相当于disabled，为true时，当react路由跳转就会触发
            when={true}
            message={location => ‘文章要保存吼，确定离开吗？’}
        />
    </div>
   )
}