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TypeScript

TypeScript was created in 2012 by Anders Hejlsberg with the intention to implement the future standard of ECMAScript 6 but also to provide a superset of syntax and features that were not part of the specification.

There are many features in TypeScript that are a superset to the ECMAScript 6 standard, including, but not limited to the following:

Optional static typing with type annotations
Interfaces
Enum types
Generics

It's important to understand that all of the features that TypeScript provides as a superset are optional. You can write pure ECMAScript 6 and not take advantage of the additional features that TypeScript provides. The TypeScript compiler will still transcompile pure ECMAScript 6 code to ECMAScript 5 without any errors.

Most of the features that are seen in TypeScript are actually already present in other languages, such as Java and C#. One goal of TypeScript was to provide language features that support workflows and better maintainability for large-scale applications.

The problem with any nonstandard language is that nobody can tell how long the language will be maintained and how fast the momentum of the language will be in the future. In terms of support, the chances are high that TypeScript, with its sponsor, Microsoft, will actually have a long life. However, there's still no guarantee that the momentum and trend of the language will keep moving at a reasonable pace. This problem does obviously not exist for standard ECMAScript 6 because it's what the web of the future is made of and what browsers will speak natively.

Still, there are valid reasons to use the extended features of TypeScript if you'd want to address the following concerns that clearly outweigh the negative implications of an uncertain future in your project:

Large applications that undergo a huge amount of changes and refactoring
Large teams that require a strict governance while working on code
Creation of type-based documentation which would otherwise be difficult to maintain

Today's version of Angular is purely based on TypeScript and therefore it's your best option if you're starting to use Angular as your framework. There are also ways to use Angular with pure ECMAScript even without using a transpiler, however, you'll be missing some great language features and support.

Within this book, we're using TypeScript for all examples as well as to create our task management system. Most of the features we're going to be using have already been or will be explained to you within this chapter. The typing system of TypeScript is pretty self-explanatory, however, if you'd like to know more about TypeScript and its features, I highly recommend that you visit the TypeScript documentation on their official website: https://www.typescriptlang.org.