Modules in TypeScript

• A module is designed to organize the code written in TypeScript.
• There are two types of modules
  • Internal Modules
  • External Modules

Internal Modules

• They are used to group classes, interfaces and functions in one group and can be exported to another module.
• There functionality is pretty much similar to namespaces.
• Internal Modules are still used in some code, but we prefer using namespaces now.
• Syntax

        module ModuleName{
            export class className{
               // statements
            }
        }
 

External Modules

• The are used to specify and load dependencies in multiple .js files.
• External modules are not used when there is only one .js file.
• Traditionally we use <script> tags to load .js file in a particular order, but these tags are not available every time, like in NodeJS.
• There are two ways of loading dependent .js files from a single .js file
  • Client Side – RequireJS
  • Server Side – NodeJS
• The syntax for declaring an external module is using keyword export and import.

Module Loader

• To load JavaScript files externally, we need a module loader.
• Module Loader is another .js library.
• Most common module loader we use is RequireJS. This is an implementation of AMD (Asynchronous Module Definition) specification.
• Instead of loading files one after the other, AMD can load them all separately, even when they are dependent on each other.