Compiler Options Option Type Default Description --allowJs boolean true Allow JavaScript files to be compiled. --allowSyntheticDefaultImports boolean module === "system" Allow default imports from modules with no default export. This does not affect code emit, just typechecking. --allowUnreachableCode boolean false Do not report errors on unreachable code. --allowUnusedLabels boolean false Do not report errors on unused labels. --baseUrl string Base directory to resolve non-relative module na

compileOnSave Setting a top-level property compileOnSave signals to the IDE to generate all files for a given tsconfig.json upon saving. { "compileOnSave": true, "compilerOptions": { "noImplicitAny" : true } } This feature is currently supported in Visual Studio 2015 with TypeScript 1.8.4 and above, and atom-typescript plugin.

Classes Documentation You can create a greeter by instantiating the Greeter object, or create a customized greeter by extending from it. Code const myGreeter = new Greeter("hello, world"); myGreeter.greeting = "howdy"; myGreeter.showGreeting(); class SpecialGreeter extends Greeter { constructor() { super("Very special greetings"); } } Declaration Use declare class to describe a class or class-like object. Classes can have properties and methods as well as a constructor. declare clas

Generic Classes A generic class has a similar shape to a generic interface. Generic classes have a generic type parameter list in angle brackets (<>) following the name of the class. class GenericNumber<T> { zeroValue: T; add: (x: T, y: T) => T; } let myGenericNumber = new GenericNumber<number>(); myGenericNumber.zeroValue = 0; myGenericNumber.add = function(x, y) { return x + y; }; This is a pretty literal use of the GenericNumber class, but you may have noticed that

Classes Classes work similarly to object literal types and interfaces with one exception: they have both a static and an instance type. When comparing two objects of a class type, only members of the instance are compared. Static members and constructors do not affect compatibility. class Animal { feet: number; constructor(name: string, numFeet: number) { } } class Size { feet: number; constructor(numFeet: number) { } } let a: Animal; let s: Size; a = s; //OK s = a; //OK

Call the script from a view In the Solution Explorer, open Views Home Index.cshtml. Change the code to be the following: @{ ViewBag.Title = "Home Page"; } <script src="~/Scripts/App/app.js"></script> <div id="message"></div> <div> Compiler: <input id="compiler" value="TypeScript" onkeyup="document.getElementById('message').innerText = sayHello()" /><br /> Framework: <input id="framework" value="ASP.NET" onkeyup="document.getElementById('m

Class Decorators A Class Decorator is declared just before a class declaration. The class decorator is applied to the constructor of the class and can be used to observe, modify, or replace a class definition. A class decorator cannot be used in a declaration file, or in any other ambient context (such as on a declare class). The expression for the class decorator will be called as a function at runtime, with the constructor of the decorated class as its only argument. If the class decorator re

Boolean The most basic datatype is the simple true/false value, which JavaScript and TypeScript call a boolean value. let isDone: boolean = false;

Browserify Now let’s move this project from Node to the browser. To do this, we’d like to bundle all our modules into one JavaScript file. Fortunately, that’s exactly what Browserify does. Even better, it lets us use the CommonJS module system used by Node, which is the default TypeScript emit. That means our TypeScript and Node setup will transfer to the browser basically unchanged. First, install browserify, tsify, and vinyl-source-stream. tsify is a Browserify plugin that, like gulp-typescri

Block-scoped variable capturing When we first touched on the idea of variable capturing with var declaration, we briefly went into how variables act once captured. To give a better intuition of this, each time a scope is run, it creates an “environment” of variables. That environment and its captured variables can exist even after everything within its scope has finished executing. function theCityThatAlwaysSleeps() { let getCity; if (true) { let city = "Seattle"; getCity = functio