Modules in TypeScript are a powerful feature that allows for the organization and encapsulation of code within a project. They play a crucial role in structuring and maintaining large codebases by enabling developers to divide their code into smaller, manageable, and reusable pieces. In TypeScript, as in modern JavaScript (ECMAScript 2015 and later), any file containing a top-level import or export is considered a module. Conversely, a file without any top-level import or export declarations is treated as a script whose contents are available globally[4].
Modules execute within their own scope, not in the global scope, which means that variables, functions, classes, interfaces, etc., defined in a module are not visible or accessible outside the module unless they are explicitly exported using the export statement. To use these exported members in other modules, they must be imported using the import statement[15].
TypeScript modules can be divided into two categories: internal and external modules. Internal modules (formerly known as "namespaces") are used for organizing code within a single project, allowing for the logical grouping of functionality. External modules, on the other hand, are more aligned with the concept of modules in ES2015 and are used to specify and load dependencies between multiple files or modules[6].
Modules help manage the scope of code, preventing naming collisions and facilitating code reuse. They are part of the ECMAScript standard and are well-supported in modern JavaScript environments, making them a good choice for organizing code in TypeScript projects[3].
TypeScript supports various module formats, including CommonJS and ES Modules, allowing developers to target different runtime environments, such as Node.js or web browsers. The module format can be specifie...
