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
TypeScript Tools and Framework Options

Declaration Files and Strict Compiler Options

One of the most appealing facets of JavaScript development is the wealth of external JavaScript libraries that have already been published, such as jQuery, Knockout, Underscore, Lodash, or Moment. As we know, TypeScript generates JavaScript, so we can easily use JavaScript libraries in TypeScript. We have already seen how TypeScript uses syntactic sugar to enhance our JavaScript development experience by providing a strong typing mechanism. If we are using JavaScript libraries, however, how do we apply this sugar to existing JavaScript or JavaScript libraries? The answer is relatively simple—declaration files.

A declaration file is a special type of file used by the TypeScript compiler. It is marked with a .d.ts extension, and is then used by the TypeScript compiler within the compilation step. Declaration files are similar...