Lodash在angular2声明var_：任何不工作 [英] Lodash in angular2, declare var_:any not working

问题描述

我用我angular2应用lodash。通过使用宣布VAR _：​​任何我在做lodash操作，如 _ findIndex（...）。现在我面临的一个问题。有时在加载页面我得到如下错误

I am using lodash in my angular2 app. by using declare var _: any; i am doing lodash operation such as _.findIndex(...) . Now i am facing one issue. sometimes while loading page i am getting error as below

EXCEPTION: ReferenceError: _ is not defined

如何避免这种情况？
正如我的假设，lodash code为前执行申报VAR _：​​任何

推荐答案

在事实上，这取决于方式来配置/包括lodash库到你的HTML页面：

In fact, it depends on the way to configure / include the lodash library into your HTML page:

• 提供lodash.js文件到一个剧本元素。通过这种方式，lodash可以作为一个全局变量（ _ ）到应用程序。在这种情况下，你需要定义它利用打字稿的环境声明：

• Include the lodash.js file into a script element. This way, lodash is available as a global variable (_) into the application. In this case, you need to define it leveraging ambient declarations of TypeScript:

declare var _: any;

配置lodash.js文件到SystemJS配置即可。以这种方式，在lodash库将检测其将一个模块加载内使用，因此将其自身注册为一个模块并返回 _ 可变进出口。在这种情况下，你需要使用进口来得到它。因为 _ 变量直接设置成出口，你需要导入这种方式：

Configure the lodash.js file into the SystemJS configuration. In this way, the lodash library will detect that it will be used within a module loader so it will register itself as a module and return the _ variable into exports. In this case, you need to use an import to get it. Since the _ variable is directly set into exports, you need to import it this way:

import _ from 'lodash';

对应的配置是：

System.config({
  (...)
  map: {
    lodash: 'node_modules/lodash/lodash.js'
  },
  meta: {
    lodash: { format: 'amd' }
  }
});

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