Dart is a new platform
for scalable web app engineering.

Language
Libraries
Tools
Compilation to JavaScript

Current stable version of Dart: [calculating]

See Dart

About 5 minutes

Dart is class based and object oriented, without being dogmatic.

See code

Write Dart

Under an hour

Follow this code lab to create a Dart web app, even if you've never written a web app before.

Write code

Dive deep

About 1 day

Dart has lots of tools, libraries, and documentation, plus a developer community.

Learn more

Dart runs in modern web browsers and on the server.

Dart is new, yet familiar

Easy to learn
Concise
Optionally typed
Modular

You can probably already read and even write Dart code. See more samples.

import 'dart:math' show Random;        // Import a class from a library.

void main() {                          // The app starts executing here.
  print(new Die(n: 12).roll());       // Print a new object's value. Chain method calls.
}

class Die {                            // Define a class.
  static Random shaker = new Random(); // Define a class variable.
  int sides, value;                    // Define instance variables.

  String toString() => '$value';      // Define a method using shorthand syntax.

  Die({int n: 6}) {                   // Define a constructor.
    if (4 <= n && n <= 20) {
      sides = n;
    } else {
      throw new ArgumentError(/* */);  // Support for errors and exceptions.
    }
  }
  int roll() {                         // Define an instance method.
    return value = shaker.nextInt(sides); // Get a random number.
  }
}

Write less. Say more.

import 'dart:math' show PI;

List shapes = [];                     // Use literals to create lists.
addShape(shape) => shapes.add(shape); // Function shorthand syntax.

main() {
  // The cascade operator (..) saves you from repetitive typing.
  addShape(new Ellipse(10, 20)..rotation = 45*PI/180
                              ..color = 'rgb(0,129,198)'
                              ..outlineWidth = 0);

  // You can easily insert expression values into strings.
  print('Area of the first shape: ${shapes[0].area}');
}

class Ellipse extends Shape {
  num minorAxis, majorAxis;
  // Syntactic sugar to set members before the constructor body runs.
  Ellipse(this.minorAxis, this.majorAxis);

  static const num C = PI/4;
  num get area => C*majorAxis*minorAxis;  // A property implemented with a getter.
}

Add types to your code to help people and tools. Or don’t. Dart is truly dynamic.

While prototyping, code freely without worrying about types.

// A function without types.
recalculate(origin, offset, estimate) {
  // ...
}

During production, use types to learn about errors early, communicate intent, and get help with code completion.

// A function with types (and an optional parameter).
num recalculate(Point origin, num offset, {bool estimate: false}) {
  // ...
}

Structure that scales. Organize your code with functions, classes, mixins, and libraries.

Dart’s comprehensive libraries give you lots of choices

Collections
Async
HTML
Testing

Every app can use lists, sets, and maps, all provided by Dart's core library.

Map famousDuos = { 'Han Solo': 'Chewbacca',      // Map literal.
                   'Bonnie': 'Clyde',
                   'Laurel': 'Hardy' };
List myFriends = [ 'Seth', 'Kathy', 'Shailen' ]; // List literal.

// Create lists and maps from Iterable objects.
List shuffledSidekicks = new List.from(famousDuos.values)..shuffle();
Map mixedDuos = new Map.fromIterables(famousDuos.keys, shuffledSidekicks);

// Iteration.
mixedDuos.forEach((k, v) { print('$k, $v'); });

// Some lists, maps, and sets are growable.
Set setOfMyFriends = new Set.from(myFriends);
Set famousPeople = new Set.from(famousDuos.values);
famousPeople.addAll(famousDuos.keys);

// Rich set of functionality for collections.
print(famousPeople.intersection(setOfMyFriends).isEmpty);
print(famousPeople.union(setOfMyFriends).length);

Dart's Future and Stream classes provide a consistent interface to values that aren’t yet available.

// Get a stream of key-press events from an element:
querySelector('textarea').onKeyPress

  // Filter the stream, getting a stream of events only for certain key codes:
  .where((e) => e.keyCode >= 32 && e.keyCode <= 122)

  // Convert those key codes, getting a stream of corresponding characters:
  .map((e) => new String.fromCharCode(e.charCode))

  // Ask for the first character, getting a Future.
  .first

  // When the Future completes, print the first character to the console.
  .then((char) => print('First char=$char'));

Dart’s HTML library unlocks the power of the modern browser, smoothing over browser differences.

import 'dart:html';
import 'dart:convert' show JSON;

void main() {
  querySelector('#getColors').onClick.listen(showColors); // Event handling.
}
void showColors(Event e) {
  HttpRequest.getString('colors.json')             // One-line HTTP request.
      .then((String jsonString) {                   // Uses Futures and Streams.
        UListElement colors = querySelector('#colors');  // DOM element types.
        List colorList = JSON.decode(jsonString);
        for (int i = 0; i < colorList.length; i++) {
          colors.children.add(                      // Dynamic DOM manipulation.
            new LIElement()..text = colorList[i]    // Dynamic element creation.
             ..style.color = colorList[i]           // Uniform CSS styles.
             ..style.fontFamily = 'Marker Felt');
        }
      })
      .catchError((_) { /* Handle error. */ });
}

Use Dart's unit testing and mocking libraries to make sure your app keeps working well.

import 'package:unittest/unittest.dart';
import 'dart:math' show Point;

main() {
  Point a = new Point(2, 15);
  Point b = new Point(7, 3);

  test('point distances', () {
    expect(a.distanceTo(b), equals(13));
  });
  test('point magnitude close to', () {
    expect(a.magnitude, closeTo(15, .25));
  });
  test('point magnitude greater than', () {
    expect(a.magnitude, greaterThan(b.magnitude));
  });
  test('point == operator', () {
    expect(a == b, equals(false));
  });
}

Compilation to JavaScript lets you deploy Dart apps now

Support for all modern browsers
Tree shaking
Minifying

Dart web apps run in all modern browsers.

Use lots of libraries? That’s OK. Tree shaking gets rid of the stuff you don’t need.

Shrink your code before you deploy to generate faster-loading JavaScript.

Dart is used to build amazing apps

“Dart offers a sane and consistent development experience for modern web applications. It really is exactly what we were looking for.”

Blossom

“We took a team of developers unfamiliar with Dart and were able to ship a sales force automation application in under six months. I think that's pretty amazing productivity.”

Google CRM

“Being able to work well at scale is extremely important, and Dart is instrumental to this effort.”

Mandrill

“When we first started exploring Dart, the team was very excited about its potential. After using it with Montage, we're even more convinced about its future.”

Montage

See who else is using Dart.

Dart’s tools help you be productive

Dart Editor is the easiest way to get started, helping you edit, debug, and run Dart apps. When you download Dart, you get Dart Editor and other tools, as well:

Pub package manager

The easiest way to get and share Dart code, pub keeps your packages up to date, handling versioning and dependency.

Dev Server

Automatically generate assets using pub’s dev server.

Dartium

Experience zero-compile edit/refresh cycles. This build of Chromium includes the Dart VM.

(For more download options, go to the download page.)