Lodash in angular2, declare var_:any not working

Question

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

Answer 1

If you are using TypeScript, then you need to import the library in your file:

import _ from 'lodash';

Have a look at a simular question: angular2 failing lodash import

Answer 2

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

• 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;
  

• 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';
  

  The corresponding configuration would be:

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