Access to Script at ‘…’ from origin ‘null’ has been blocked by CORS policy: Invalid response. Origin ‘null’ is therefore not allowed access.错误原因及解决办法

网上下载了一个 js 特效项目，直接用浏览器打开网页无法正确显示特效，通过谷歌浏览器开发者工具查看显示有错误：

Access to Script at 'file:///home/../.../JavaScript/src/index.js' from origin 'null' has been blocked by CORS policy: Invalid response. Origin 'null' is therefore not allowed access.

这是因为项目中用到了ES6 模块，而ES6 模块须遵守同源政策。如果要预览，需要从本地服务器运行脚本，直接用浏览器打开文件将无法运行。