module.exports怎么理解？(function {})(this, function(){})的(function {})和this參數怎么理解？(function webpackUniversalModuleDefinition(root, factory) {    if(typeof exports === 'object' && typeof module === 'object')        module.exports = factory(require("echarts"));    else if(typeof define === 'function' && define.amd)        define(["echarts"], factory);    else if(typeof exports === 'object')        exports["echarts-gl"] = factory(require("echarts"));    else        root["echarts-gl"] = factory(root["echarts"]);})(this, function(__WEBPACK_EXTERNAL_MODULE_0__) {return /******/ (function(modules) { }