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diff --git a/typescript.html.markdown b/typescript.html.markdown new file mode 100644 index 00000000..fd22cbef --- /dev/null +++ b/typescript.html.markdown @@ -0,0 +1,139 @@ +--- +language: TypeScript +contributors: + - ["Philippe Vlérick", "https://github.com/pvlerick"]] +filename: learntypescript.ts +--- + +TypeScript is a language that aims at easing development of large scale applications written in JavaScript. +TypeScript adds common concepts such as classes, modules, interfaces, generics and (optional) static typing to JavaScript. +It is a superset of JavaScript: all JavaScript code is valid TypeScript code so it can be added seamlessly to any project. The TypeScript compiler emitts JavaScript. + +This article will focus only on TypeScript extra syntax, as oposed to [JavaScript] (../javascript/). + +To test TypeScript's compiler, head to the [Playground] (http://www.typescriptlang.org/Playground) where you will be able to type code, have auto completion and directly see the emitted JavaScript. + +```ts +//There are 3 basic types in TypeScript +var isDone: boolean = false; +var lines: number = 42; +var name: string = "Anders"; + +//..When it's impossible to know, there is the "Any" type +var notSure: any = 4; +notSure = "maybe a string instead"; +notSure = false; // okay, definitely a boolean + +//For collections, there are typed arrays and generic arrays +var list: number[] = [1, 2, 3]; +//Alternatively, using the generic array type +var list: Array<number> = [1, 2, 3]; + +//For enumerations: +enum Color {Red, Green, Blue}; +var c: Color = Color.Green; + +//Lastly, "void" is used in the special case of a function not returning anything +function bigHorribleAlert(): void { + alert("I'm a little annoying box!"); +} + +//Functions are first class citizens, support the lambda "fat arrow" syntax and use type inference +//All examples are equivalent, the same signature will be infered by the compiler, and same JavaScript will be emitted +var f1 = function(i: number) : number { return i * i; } +var f2 = function(i: number) { return i * i; } //Return type infered #TODO bug! +var f3 = (i : number) : number => { return i * i; } +var f4 = (i: number) => { return i * i; } //Return type infered +var f5 = (i: number) => i * i; //Return type infered, one-liner means no return keyword needed + +//Interfaces are structural, anything that has the properties is compliant with the interface (duck typing) +interface Person { + name: string; + //Optional properties, marked with a "?" + age?: number; + //And of course functions + move(): void; +} + +//..Object that implements the "Person" interface +var p : Person = { name: "Bobby", move : () => {} }; //Can be treated as a Person since it has the name and age properties +//..Objects that have the optional property: +var validPerson : Person = { name: "Bobby", age: 42, move: () => {} }; +var invalidPerson : Person = { name: "Bobby", age: true }; //Is not a person because age is not a number + +//..Interfaces can also describe a function type +interface SearchFunc { + (source: string, subString: string): boolean; +} +//..Only the parameters' types are important, names are not important. +var mySearch: SearchFunc; +mySearch = function(src: string, sub: string) { + return src.search(sub) != -1; +} + +//Classes - members are public by default +class Point { + //Properties + x: number; + + //Constructor - the public/private keywords in this context are shortcuts to generate the code for a property + //Equivalent to "x" in this case + //Default values are also supported + constructor(x: number, public y: number = 0) { + this.x = x; + } + + //Functions + dist() { return Math.sqrt(this.x * this.x + this.y * this.y); } + + //Static members + static origin = new Point(0, 0); +} + +var p1 = new Point(10 ,20); +var p2 = new Point(25); //y will be 0 + +//Inheritance +class Point3D extends Point { + constructor(x: number, y: number, public z: number = 0) { + super(x, y); //Explicit call to the super class constructor is mandatory + } + + //Overwrite + dist() { + var d = super.dist(); + return Math.sqrt(d * d + this.z * this.z); + } +} + +//Modules, "." can be used as separators for sub modules +module Geometry { + export class Square { + constructor(public sideLength: number = 0) { + } + area() { + return Math.pow(this.sideLength, 2); + } + } +} + +var s1 = new Geometry.Square(5); + +//..Local alias for rreferencing a module +import G = Geometry; + +var s2 = new G.Square(10); + +//Generics + +//Including references to a definition file: +/// <reference path="jquery.d.ts" /> + +``` + +## Further Reading + * [TypeScript Official website] (http://www.typescriptlang.org/) + * [TypeScript language specifications (pdf)] (http://go.microsoft.com/fwlink/?LinkId=267238) + * [Anders Hejlsberg - Introducing TypeScript on Channel 9] (http://channel9.msdn.com/posts/Anders-Hejlsberg-Introducing-TypeScript) + * [Source Code on GitHub] (https://github.com/Microsoft/TypeScript) + * [Definitely Typed - repository for type definitions] (http://definitelytyped.org/) |