TYPESCRIPTDUUG 25 SEPTEMBER 2014By Jan van Helvoort - Web Expert / @janvhelvoort

TYPESCRIPT LETS YOU WRITE JAVASCRIPTTHE WAY YOU REALLY WANT TO.

TYPESCRIPTTypesInterfacesClassesModulesFunctionsGenerics

JAVASCRIPTTYPESCRIPT IS A TYPED SUPERSET OF JAVASCRIPT THAT COMPILES TO PLAIN JAVASCRIPT.

BENEFITSCompilerType safetyAuto completionDeclaration files ( )OOPAngular.js Backend

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TYPESStringNumberBooleanArrayEnumAnyVoid

STRING / NUMBER / BOOLEANvar name: string = 'Jan';var age: number = 24;var isDutch: boolean = true;

Cannot convert 'boolean' to 'string'.

name = isDutch;

ARRAYvar list: number[] = [1, 2, 3];list.push(4);

Could not apply type 'number' to argument 1 which is of type 'string'.

list.push('five');

ENUMenum Countries { 'Netherlands', 'Belgium', 'Unkown' }var country: Countries = Countries.Netherlands;

ANYvar notSure: any = 4;notSure = "maybe a string instead";notSure = false; // okay, definitely a boolean

INTERFACESinterface IPerson { Name: string; Country: Countries; IsDutch: boolean;

callName(): string;}

INTERFACESclass person implements IPerson { }

Class person declares interface IPerson but does not implement it:Type 'person' is missing property 'Name' from type 'IPerson'.Type 'person' is missing property 'Counties' from type 'IPerson'.Type 'person' is missing property 'IsDutch' from type 'IPerson'.Type 'person' is missing property 'callName' from type 'IPerson'.

CLASSESclass person implements IPerson { public Name: string; public Country: Countries; public IsDutch: boolean;

constructor(name: string, country: Countries, isDutch: boolean) { this.Name = name; this.Country = Countries.Netherlands; this.IsDutch = isDutch; }

callName() { return this.Name; }}

CLASSES - A SHORTER WAYclass person implements IPerson { constructor(public Name: string, public Country: Countries, public IsDutch: boolean) { }

callName() { return this.Name; }}

NEW CLASSvar dave = new person('Dave Woestenborghs', Countries.Belgium, false);

GENERICSfunction identity<T>(arg: T): T { return arg;}

var output = this.identity<string>('one');

Supplied parameters do not match any signature of call target:Could not apply type 'string' to argument 1 which is of type 'number'.

var output = this.identity<string>(1);

TOOLSVisual Studio 2013 update 2Visual Studio 2012 ( )Sublime Text ( )Emacs ( )Vim ( )

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