Ember 3.0 Released

Today the Ember project is releasing version 3.0.0 of Ember.js, Ember Data, and Ember CLI. Ember 3.0 doesn't introduce any new functionality, instead it focuses the framework by removing long-deprecated APIs and support for legacy platforms. Our plans for Ember 3.0 were announced in October 2017 in The Road to Ember 3.0.

We're committed to giving every Ember codebase a path into the 3.x series. With this goal in mind, we froze API deprecations targeting Ember 3.0 back in July 2017 (Ember 2.14). We've provided a detailed deprecation guide for all APIs removals, and additionally extracted most of the features removed in 3.0 into an addon.

This blog post will help you understand what is being removed in 3.0 and what migration strategies are available. If you're interested in trying Ember for the first time today, get started by running:

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yarn global add ember-cli # Or npm install -g ember-cli
ember new my-project
cd my-project
ember serve # Then visit http://localhost:4200

Additionally, today the 3.1 beta cycle begins for these same projects. We've split out the beta release details into a separate Ember 3.1-beta blog post to keep this one focused on app migration steps and guidance.

Finally, today we're also promoting Ember 2.18 to LTS (2.18 release post). This is the last release of Ember with support for IE9, IE10, PhantomJS, and for use via Bower. Per our LTS policy, it will be supported with bug fixes for the next 5 release cycles (September 2018) and security patches for the next 9 cycles (February 2019).

Browser Support in 3.0

Ember 3.0 (including Ember.js, Ember Data, and Ember CLI) drops support for Internet Explorer 9, IE 10, and PhantomJS. If you still require support for these browsers, Ember 2.18-LTS will be supported with bug fixes until September 2018 and security fixes until February 2019 in alignment with our LTS policy.

If your application requires support for these browsers and you would like to eventually adopt Ember 3.x, we encourage you to use the LTS window to plan a transition for your users in the coming months.

The first LTS of Ember 3.x will be Ember 3.4. Any migration steps we describe for moving between Ember 2.18 and 3.0 will also apply to 2.18-LTS and 3.4-LTS.

For further details about this decision see RFC #252 and The Road to Ember 3.0: Browser Support in 3.0.

Global Build and Bower Support in 3.0

Ember 3.0 completes a re-orientation of the project away from script tag driven development. This follows a general trend in JavaScript, where frameworks and applications have embraced ahead of time (AOT) compilation to improve performance and development experience (DX).

Nearly all Ember applications already use Ember CLI for development, and most also use Ember CLI addons to bring in libraries and build-time features. As of their 3.0 releases, both Ember.js and Ember Data are only available as Ember CLI addons. This makes the codebases easier to maintain, and allows improvements we make to Ember's packaging to apply to 3rd party addons.

The legacy, script tag driven use of Ember via a "globals" build is removed in 3.0.

Builds of Ember.js and Ember Data for use with a <script> tag are no longer published as of 3.0. This includes:

  • Builds published to Bower as components/ember and components/ember-data.
  • Builds published to S3, for example at http://builds.emberjs.com/release/shas/1f05c15cfc6d9df5882f9ff7cc985f50fe68f98f/ember.min.js
  • Builds published to CDNs, for example at https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.16.2/ember.debug.js

Instead applications should make Ember a dependency via NPM or Yarn:

  • ember-source is the Ember NPM package.
  • ember-data is the Ember Data NPM package.

Most applications should already be using these packages. An exception is that many addons (and some applications) use ember-try to test against multiple versions of Ember, and may reference the Bower builds for testing beta and canary releases.

We've started published tarballs containing the NPM package for each commit to Ember.js and Ember Data. This allows you to migrate an addon's ember-try configuration away from Bower. The ember-source-channel-url addon provides an API for fetching the appropriate URL for a given channel. The latest version of Ember CLI's addon blueprint uses this API out of the box, so most addons simply need to upgrade to Ember CLI 3.0 to complete their move away from Bower.

Changes in Ember.js 3.0


Ember.js is the core of the Ember framework. It provides routing, rendering, and dependency injection features.

Ember.js 3.0 introduces no new public API or deprecations. Instead, it is comprised of bug fixes and the removal of previously deprecated public API from the 2.x cycle. This release drops support for IE9, IE10, PhantomJS, and Bower.

Updates to the Testing Defaults

In Ember 3.0 we've changed the default blueprint for generated tests to use the new testing API specified in RFC #232 and RFC #268.

You can find the final documentation for these test helpers at:

And additionally the Ember.js Testing Guides have been updated.

The testing API available in previous Ember releases remains supported and un-deprecated in 3.0. If you would like to migrate tests using the old APIs to the new API, upgrade Ember CLI and Ember then run the ember-qunit-codemod script to automate most of the change.

Computed Property Getter Assertion

Ember's computed property system requires the use of the .get( method to read the value of a computed property. For example:

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emberObject.get('someComputedProperty'); // returns the value

In some cases, application code may have incorrectly been relying on the presence of a value for the property itself, for example:

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emberObject.someComputedProperty; // an instance of ComputedPropertyDescriptor

The return value in this case is not the computed property's value, but an instance of an internal Ember class.

In Ember 3.0 reading a computed property without using get will cause an assertion failure in development. This addition of this assertion will help applications correct their currently incorrect usage, and in later 3.x releases allow us to remove the requirement to use get to read a computed property's value.

APIs Removed in 3.0

Below we've listed some of the most significant API removals in Ember.js 3.0. For a more in-depth summary see The Road to Ember 3.0: APIs Removed in Ember.js 3.0, and for an exhaustive list of removals, see the Ember.js 2.x deprecation guide.

  • The {{render}} helper has been removed. Any remaining usage should be migrated to components.
  • didInitAttrs is removed and can be replaced with init
  • Declaring an observer with dependent keys after the callback is removed. Dependent keys should be passed before the callback as described in the API docs.
  • Enumerable#contains and Array#contains methods are removed. Instead usage should be replaced with includes.
  • {{link-to}} unwrapped the model property from passed controllers. This behavior has been removed.
  • Specifying defaultLayout on a component rather than layout has been removed.
  • Ember.Handlebars.SafeString has been removed. Instead, use Ember.String.htmlSafe or the import { htmlSafe } from '@ember/string'.
  • Ember.K has been removed. Usage should be replaced with inline functions.
  • Support for legacy initializers with two arguments (container, application) has been removed in favor of a single argument of application.
  • Ember's legacy binding system, including Ember.Binding and the fooBinding micro-syntax. See the migration guide for details.
  • Ember's Map, MapWithDefault, and OrderedSet classes. These should be replaced with native features or with implementations from other libraries.

For more details on the changes in Ember.js 3.0, please review the Ember.js 3.0.0 release page.

Changes in Ember Data 3.0


Ember Data is the official data persistence library for Ember.js applications.

Ember Data 3.0 contains small bug fixes and updated test generators for the new testing APIs. Additionally this release removes previously deprecated APIs.

Below we've listed some of the most significant API removals in Ember Data 3.0. For a more in-depth summary see The Road to Ember 3.0: APIs Removed in Ember Data 3.0, and for an exhaustive list of removals, see the Ember Data 2.x deprecation guide.

For more details on the changes in Ember Data 3.0, please review the Ember Data 3.0.0 release page.

Changes in Ember CLI 3.0


Ember CLI is the command line interface for managing and packaging Ember.js applications.

Ember CLI 3.0 makes it easier to use async and await by including the addon ember-maybe-import-regenerator in the default app blueprint.

Below we've listed some of the most significant API removals in Ember CLI 3.0. For a more in-depth summary see The Road to Ember 3.0: APIs Removed in Ember CLI 3.0, and for an exhaustive list of removals, see the Ember CLI 2.x deprecation guide.

For more details on the changes in Ember CLI 3.0 and detailed upgrade instructions, please review the Ember CLI 3.0.0 release page.

Migrating to Ember 3.0


To ensure as many applications as possible make the transition from 2.x to 3.x, all public APIs removed in Ember.js 3.0 have been extracted into the ember-2-legacy addon. This addon will be supported through Ember.js 3.4, the first LTS of the 3.x series.

The addon maintains support for all APIs in the Ember.js 2.x deprecations guide. Please note that these are only APIs from Ember.js itself, and there is no extended support addon for features removed from Ember Data or Ember CLI.

Applications that need to upgrade through several versions may want to consider the ember-cli-deprecation-workflow addon to isolate individual deprecations.

Thank You!

This summer the Ember project will mark five years since Ember 1.0 was released. Every six weeks since 1.0 (well, nearly every six weeks) we've had a new set of incremental improvements to announce. That is some impressive stuff! Thank you for your continued contribution to this project, and for your participation in creating a great set of tools for building on the web.


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