Functions, Lambdas, and Execution Flow

Functions are the processing machines we use to analyze input, digest information, and apply the necessary transformations to data. Data can be provided either to transform the state of our application or return an output that will be used to shape our application’s business logic or user interactivity.

Functions in TypeScript are not that different from regular JavaScript, except that, like everything else in TypeScript, they can be annotated with static types. Therefore, they improve the compiler by providing the information it expects in their signature and the data type it aims to return, if any.

Annotating types in functions

The following example showcases how a regular function is annotated in TypeScript: