(function {})(this, function(){})的(function {})和this参数怎么理解？

Question

module.exports怎么理解？

(function {})(this, function(){})的(function {})和this参数怎么理解？

(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) { }

Answer 1

就是一个立刻调用的匿名函数

(function(root,factory){
    //root 因为直接调用所以this是全局对象,浏览器环境为window，node环境为global
    //factory() 返回1
})(this,function(){
    return 1
});

module.exports = factory(require("echarts")); node环境
define(["echarts"], factory); 第三方模块加载插件
root["echarts-gl"]; window环境