Angular + amazon-cognito-identity-js，为什么我收到错误：未定义全局

Question

从命令行：

ng new sandbox
cd .\sandbox\
ng serve

打开http://localhost:4200/。它有效。

npm install --save amazon-cognito-identity-js

在\src\app\sign-up\sign-up.component.ts里面添加这行代码：

import * as AmazonCognitoIdentity from 'amazon-cognito-identity-js';

添加构造函数：

  constructor() {
    new AmazonCognitoIdentity.CognitoUserPool({});
  }

刷新http://localhost:4200/。

页面为空白。出现控制台错误：

Uncaught ReferenceError: global is not defined
    at Object../node_modules/buffer/index.js (index.js:43)
    at __webpack_require__ (bootstrap:76)
    at Object../node_modules/amazon-cognito-identity-js/es/AuthenticationHelper.js (AuthenticationHelper.js:1)
    at __webpack_require__ (bootstrap:76)
    at Object../node_modules/amazon-cognito-identity-js/es/index.js (index.js:1)
    at __webpack_require__ (bootstrap:76)
    at Object../src/app/app.component.ts (main.js:94)
    at __webpack_require__ (bootstrap:76)
    at Object../src/app/app.module.ts (app.component.ts:9)
    at __webpack_require__ (bootstrap:76)

解决此错误的最佳方法是什么？

Answer 1

将此作为/src/polyfills.ts的最后一行

(window as any).global = window