node.js – 在角度2中使用system.config.js文件有什么用？

@H_489_4@ var map,packages,var config是做什么的.并且还解释了map和package对象的所有配置属性.是否有可用配置的文档？

这是我的系统配置文件

/**
 * System configuration for Angular samples
 * Adjust as necessary for your application needs.
 */
(function (global) {
  System.config({
    paths: {
      // paths serve as alias
      'npm:': 'node_modules/'
    },// map tells the System loader where to look for things
    map: {
      // our app is within the app folder
      app: 'app',// angular bundles
      '@angular/core': 'npm:@angular/core/bundles/core.umd.js','@angular/common': 'npm:@angular/common/bundles/common.umd.js','@angular/compiler': 'npm:@angular/compiler/bundles/compiler.umd.js','@angular/platform-browser': 'npm:@angular/platform-browser/bundles/platform-browser.umd.js','@angular/platform-browser-dynamic': 'npm:@angular/platform-browser-dynamic/bundles/platform-browser-dynamic.umd.js','@angular/http': 'npm:@angular/http/bundles/http.umd.js','@angular/router': 'npm:@angular/router/bundles/router.umd.js','@angular/forms': 'npm:@angular/forms/bundles/formS.UR_797_11845@d.js',// other libraries
      'rxjs': 'npm:rxjs','angular-in-memory-web-api': 'npm:angular-in-memory-web-api/bundles/in-memory-web-api.umd.js','fscopy': 'npm:fs-extra/lib/copy/index.js','file-system': 'npm:file-system/file-system.js'
    },// packages tells the System loader how to load when no filename and/or no extension
    packages: {
      app: {
        main: './main.js',defaultExtension: 'js'
      },rxjs: {
        defaultExtension: 'js'
      },fs: {
        defaultExtension: 'js'
      }
    }
  });
})(this);