cookie的作用无需多言，自己封装一个cookie，不停地复制黏贴页颇为麻烦，在这里，有npm为我们封装好的插件js-cookie: https://www.npmjs.com/package/js-cookie。
1.直接饮用cdn：<script src="https://cdn.jsdelivr.net/npm/js-cookie@2/src/js.cookie.min.js">
2.本地下载下来后：<script src="/path/to/js.cookie.js">
3.模块化开发时: import Cookies from ‘js-cookie‘
使用方法：
Basic Usage Create a cookie, valid across the entire site: Cookies.set(‘name‘, ‘value‘); Create a cookie that expires 7 days from now, valid across the entire site: Cookies.set(‘name‘, ‘value‘, { expires: 7 }); Create an expiring cookie, valid to the path of the current page: Cookies.set(‘name‘, ‘value‘, { expires: 7, path: ‘‘ }); Read cookie: Cookies.get(‘name‘); // => ‘value‘ Cookies.get(‘nothing‘); // => undefined Read all visible cookies: Cookies.get(); // => { name: ‘value‘ } Delete cookie: Cookies.remove(‘name‘); Delete a cookie valid to the path of the current page: Cookies.set(‘name‘, ‘value‘, { path: ‘‘ }); Cookies.remove(‘name‘); // fail! Cookies.remove(‘name‘, { path: ‘‘ }); // removed! IMPORTANT! when deleting a cookie, you must pass the exact same path and domain attributes that was used to set the cookie, unless you‘re relying on the default attributes. Note: Removing unexisting cookie does not raise any exception nor return any value