定义：jquery是第三方开发的*（先下载，再使用），执行DOM操作的，极简化的函数库（jquery使用函数解决一切问题，没有属性）。（第一方：自己写 第二方：浏览器自带）好处：简单，解决了大部分浏览器兼容性问题。问题：简化的不彻底，只是简化了语句，没有减少步骤。只有pc端，没有移动端。jq下载官网：jquery.com版本 1.x支出旧浏览器（IE8）版本，不支持ES6语法。2.x不再支持旧浏览

[渲染层网络层错误] Failed to load local image resource /upload/getObject/undefinedthe server responded with a status of 500 (HTTP/1.1 500 Internal Server Error)(env: Windows,mp,1.05.2106300; lib: 2.19.6)

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ERROR Failed to compile with 1 errorTemplates should only be responsible for mapping the state to the UI. Avoid placing tags with side-effects in your templates, such as <script>, as they will n

uni-app 允许小程序出现这个错误信息是因为没有在hbuildex x中进行运行，直接用小程序打开了

Access to XMLHttpRequest at 'http://www.xxxxxxx.cn/xxxxx/xxxxx/xxxxx/login' from origin 'http://xx.x.x.xx:xxxx' has been blocked by CORS policy: Response to preflight request doesn't pass access contr