TypeScript introduction

In newer web application development we are more and more diving into client side scripts. Slowly AJAX calls are completely or at least mostly replacing regular post backs for rich user experience. Somewhere we are dealing HTMLs returns or just interacting with model but with time we are ending up writing lot of JavaScript on pages or dedicated JavaScript files.

After starting project, in short of span of time we are ending up with lot of scripts. Writing those script itself is problematic process as we do not get any type safety and on execution only we can know we have missed typed or added some variable in place of some other type. Mostly through comments only we are understanding the code association with pages unless we put JavaScript in respective pages or with naming JS according to respective page names. I know we can use some OOPS concept or JS framework like Backbone, Knockout etc. to manage things through MVC or MVVM approach. Those are really good way to handle JavaScript but we do not get any type safety as it is JavaScript.

I am a really great fan of OOPS concept but have never tried on JavaScript. May be I do not understand JavaScript much or too lazy to write extra script to manage it. I was looking for solution for easy and happy scripting then I come to know TypeScript.

What is TypeScript?

TypeScript is an open source scripting language and super-set of JavaScript with type safety. That means whatever JavaScript script code we have written till now is TypeScript only. Oh! what is the point then if it is TypeScript and how that type safety works. JavaScript is subset of TypeScript, where all JavaScript code will workout without doing anything extra but for taking advantage of TypeScript we can follow there guideline.

What are guidelines of TypeScript and how to code?

It is more of like JScript .NET or could be related with C#. It is pretty simple to catch up with TypeScript if we have worked on any OOP languages. It is having classes, interfaces, modules (namespace), generics, type declaration, most lovely compile time checks etc.

For getting started with we can look into http://www.typescriptlang.org/Playground

How it works?

The extension of JavaScript is ts. It comes with tsc compiler which could be downloaded from http://www.typescriptlang.org/#Download. The compiler compiles the ts file into JavaScript files to have compatibility with any browser and doing every hard work for us.

TypeScript helping tools

For taking advantage of various JavaScript libraries, it is having huge list of type definition which could be found on https://github.com/borisyankov/DefinitelyTyped.

By importing those we can have type safety checks. Ex: jQuery has lot of functionality with various types declared in it. By importing the definition we can have intellisense with type checks.

Web Essential is an extension of Visual Studio through which we can have JavaScript file generation at a time of writing only, which you might have seen from Playground link.

TypeLITE is a tool to generate up TypeScript interfaces according to server side classes or models.

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