Book Image

Mastering TypeScript 3 - Third Edition

By : Nathan Rozentals
Book Image

Mastering TypeScript 3 - Third Edition

By: Nathan Rozentals

Overview of this book

TypeScript is both a language and a set of tools to generate JavaScript. It was designed by Anders Hejlsberg at Microsoft to help developers write enterprise-scale JavaScript. Starting with an introduction to the TypeScript language, before moving on to basic concepts, each section builds on previous knowledge in an incremental and easy-to-understand way. Advanced and powerful language features are all covered, including asynchronous programming techniques, decorators, and generics. This book explores many modern JavaScript and TypeScript frameworks side by side in order for the reader to learn their respective strengths and weaknesses. It will also thoroughly explore unit and integration testing for each framework. Best-of-breed applications utilize well-known design patterns in order to be scalable, maintainable, and testable. This book explores some of these object-oriented techniques and patterns, and shows real-world implementations. By the end of the book, you will have built a comprehensive, end-to-end web application to show how TypeScript language features, design patterns, and industry best practices can be brought together in a real-world scenario.
Table of Contents (16 chapters)
Free Chapter
1
TypeScript Tools and Framework Options

Module merging

As we now know, the TypeScript compiler will automatically search through all the .d.ts files in our project to pick up declaration files. If these declaration files contain the same module name, the TypeScript compiler will merge these two declaration files and use a combined version of the module declarations.

Imagine that we have a file named MergedModule1.d.ts, containing the following definition:

declare module MergedModule { 
    function functionA() : void; 
} 

And we also have a second file, named MergedModule2.d.ts, that contains the following definition:

declare module MergedModule { 
    function functionB() : void; 
} 

Now, the TypeScript compiler will merge these two modules as if they were a single definition:

declare module MergedModule { 
    function functionA() : void; 
    function functionB() : void; 
} 

This will allow both functionA and functionB...