Modules

As our applications scale and grow in size, there will be a time when we need to organize our code better and make it sustainable and more reusable. Modules are responsible for this need, so let's take a look at how they work and how we can implement them in our application.

A module works at a file level, where each file is the module itself, and the module name matches the filename without the .ts extension. Each member marked with the export keyword becomes part of the module's public API:

my-service.ts

export class MyService {

    getData() {}

}

To use this module and its exported class, we need to import it:

import { MyService } from './my-service';

Notice that the./my-service path is relative to the location of the file that imports the module. If the module exports more than one artifact, we place them inside the curly braces one by one, separated with a comma:

export class MyService {

    getData() {}

}

export const PI = 3.14;

import { MyService, PI } from './my-service'; 

In the preceding example, MyService exports the getData method and the PI variable in one go.