Blog Post - Types for TypeScript 2.0.md

Preview: Type Acquisition in TypeScript 2.0

Today we'd like to show you a new experience for TypeScript developers, and offer you to try it out in our nightly build.

Getting type definitions for libraries is a common task that so far has been handled by third-party tools. Our goal with this new suite of features is to simplify and streamline the process. This new experience leverages existing tools in the JavaScript ecosystem, offering a single-step commandline process for getting type definitions.

Let's walk through using the example of getting types for lodash

Step 1: npm install @types/lodash

On the commandline:

npm install @types/lodash

Step 2: Ready!

There's no step 2 in this process! With the type definitions installed in @types/, we can use them immediately.

If you're using lodash from the global scope, you can write:

// consumer.ts
_.map([1, 2, 3], function(n) { return n * 3; });

If you're using a module loader to load the script, you can write:

// consumer.ts
import * as _ from 'lodash';

_.map([1, 2, 3], function(n) { return n * 3; });

You can now compile as usual by running:

tsc consumer.ts

This functionality is available now in the nightly builds of TypeScript (npm install typescript@next).

More

If we install types for a library with dependencies, the dependencies are install automatically:

npm install @types/jquery-ui

// jQuery and jQuery UI definitions both installed, everything's OK
$('myElem').dialog();