Add TypeScript The next step is to add a folder for TypeScript. We’ll just call it scripts.

Symbol.unscopables An Object whose own property names are property names that are excluded from the ‘with’ environment bindings of the associated objects.

Iterables An object is deemed iterable if it has an implementation for the Symbol.iterator property. Some built-in types like Array, Map, Set, String, Int32Array, Uint32Array, etc. have their Symbol.iterator property already implemented. Symbol.iterator function on an object is responsible for returning the list of values to iterate on.

Putting it all together Just run: webpack Now open up index.html in your favorite browser and everything should be ready to use! You should see a page that says “Hello from TypeScript and React!”

Using npm npm install -g typescript@next

Destructuring Another ECMAScript 2015 feature that TypeScript has is destructuring. For a complete reference, see the article on the Mozilla Developer Network. In this section, we’ll give a short overview.

Readonly modifier You can make properties readonly by using the readonly keyword. Readonly properties must be initialized at their declaration or in the constructor. class Octopus { readonly name: string; readonly numberOfLegs: number = 8; constructor (theName: string) { this.name = theName; } } let dad = new Octopus("Man with the 8 strong legs"); dad.name = "Man with the 3-piece suit"; // error! name is readonly.

Import a single export from a module import { ZipCodeValidator } from "./ZipCodeValidator"; let myValidator = new ZipCodeValidator(); imports can also be renamed import { ZipCodeValidator as ZCV } from "./ZipCodeValidator"; let myValidator = new ZCV();

Global Libraries A global library is one that can be accessed from the global scope (i.e. without using any form of import). Many libraries simply expose one or more global variables for use. For example, if you were using jQuery, the $ variable can be used by simply referring to it: $(() => { console.log('hello!'); } ); You’ll usually see guidance in the documentation of a global library of how to use the library in an HTML script tag: <script src="http://a.great.cdn.for/someLib.js">

Find and Install Declaration Files For JavaScript library users, the Consumption section offers a few simple steps to locate and install corresponding declaration files.