Large scale JavaScript application development made easy.

1. Introducing TypeScript
Large scale JavaScript application
development made easy
By Remo H. Jansen

2. What is TypeScript?
TypeScript is a typed superset of JavaScript.
Compiles to plain JavaScript.
Any IDE. Any browser. Any host. Any OS.
Open Source.
Based on open standards (ES6, ES7...).

3. JavaScript is TypeScript!
“We’re excited to announce that we
have converged the TypeScript and
AtScript languages, and that Angular 2,
the next version of the popular
JavaScript library for building web sites
and web apps, will be developed with
TypeScript”

4. Why do we need TypeScript? (PART I)
“As a system evolves, its complexity increases
unless steps are taken to reduce it”
JavaScript was not designed to deal with the
level of complexity required to meet today’s
needs.

5. Complex !== Complicated
Complicated implies being difficult to understand but with time and
effort, ultimately knowable.
Complex describes the interactions between a number of entities. If
the number of entities and interactions between them increase
we will get to a point where it would be impossible to know and
understand all of them.

7. TypeScript is the future of JavaScript
TypeScript allows us to use ES6 and ES7 today!
We can use the --target compiler option to
specify ECMAScript target version: ES3, ES5 or
ES6.

8. Classes

9. Inheritance

10. Modules
We can use the --module
compiler option to specify
module code generation:
CommonJS
AMD
System
UMD

11. Generators “Synchronous Looking
Asynchronous Code”

12. Async / Await

13. Decorators
Note: The code snippets above are part of an open-source project I’m
working on. You can learn more about it at http://inversify.io/
● Metadata Reflection API

14. Why do we need TypeScript? (PART II)
“Large codebases are more difficult to maintain
when they are written in dynamic languages”

15. TypeScript goes beyond ES6 & ES7
TypeScript is a strongly typed programming
language
TypeScript introduces some great design-time
features that are not available in ES6 or ES7.

16. Namespaces
● AKA Internal modules
● It is recommended to
use ES6 modules
instead

17. Types
● Design-time only
● Type inference
● Optional type
annotations
● Type guards
● Union types
● Intersection types

18. Interfaces
● Design-time only
● Structural type system
● Type definitions (.d.ts files)

19. Generics
● Design-time only
● Generic constraints can be
declared

20. Getting started with TypeScript!
http://www.typesc
riptlang.org/Playgr
ound
https://github.com
/remojansen/ts-
vscode-boilerplate

21. Questions?

22. Thanks!
● Join the Dublin TypeScript Meetup to learn more!
● Get 20% off my book “Learning TypeScript” (eBook)
using promo code PACKT20 at www.packtpub.com