Create 2017-03-19-ember-2-12-released.md

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+---
+title: Ember 2.12 and 2.13 Beta Released
+author: Matthew Beale, Brendan McLoughlin, Robert Jackson
+tags: Releases
+---
+
+Today the Ember project is releasing version 2.12.0 of Ember.js, Ember Data, and Ember CLI.
+
+This release kicks off the 2.13 beta cycle for all sub-projects. We encourage our
+community (especially addon authors) to help test these beta builds and report
+any bugs before they are published as a final release in six weeks' time. The
+[ember-try](https://github.com/ember-cli/ember-try) addon is a great way to
+continuously test your projects against the latest Ember releases.
+
+You can read more about our general release process here:
+
+- [Release Dashboard](http://emberjs.com/builds/)
+- [The Ember Release Cycle](http://emberjs.com/blog/2013/09/06/new-ember-release-process.html)
+- [The Ember Project](http://emberjs.com/blog/2015/06/16/ember-project-at-2-0.html)
+- [Ember LTS Releases](http://emberjs.com/blog/2016/02/25/announcing-embers-first-lts.html)
+
+---
+
+## Ember.js
+
+Ember.js is the core framework for building ambitious web applications.
+
+### Changes in Ember.js 2.12
+
+The
+2.12.0 release is an Ember.js Long-Term Support candidate. In six weeks, the 2.12.x series
+will become the latest LTS release and six weeks after that the 2.8 LTS branch
+will no longer receive bugfix patches.
+
+For more information about Ember's LTS policies, see the
+[announcement blog
+post](http://emberjs.com/blog/2016/02/25/announcing-embers-first-lts.html) and
+[builds page](http://emberjs.com/builds/).
+
+Ember 2.12 implements the `factoryFor` API as described in [RFC #150](https://github.com/emberjs/rfcs/blob/master/text/0150-factory-for.md).
+This public API replaces the intimate API of `_lookupFactory`, and additionally
+discourages developers from setting properties on classes returned from the
+container. For more information about this API see the [API
+docs](http://emberjs.com/api/classes/ContainerProxyMixin.html#method_factoryFor)
+and [`_lookupFactory` deprecation guide](http://emberjs.com/deprecations/v2.x/#toc_migrating-from-_lookupfactory-to-factoryfor).
+
+Addon authors and others should consider if the
+[ember-factory-for-polyfill](https://github.com/rwjblue/ember-factory-for-polyfill)
+addon can help them avoid the deprecation warning for `_lookupFactory`.
+
+Additionally, this release of Ember contains an incremental performance
+improvement for the Glimmer rendering engine (you may have seen it
+referred to as the "binary VM"). By avoiding runtime
+compilation of syntax objects, initial rendering performance will benefit.
+
+#### Deprecations in Ember 2.12
+
+- The `Ember.K` utility function is deprecated per [RFC #178](https://github.com/emberjs/rfcs/blob/master/text/0178-deprecate-ember-k.md).
+  See the [deprecation guide](http://emberjs.com/deprecations/v2.x/#toc_code-ember-k-code)
+  and pull request [#14751](https://github.com/emberjs/ember.js/pull/14751)
+  for additional details.
+
+- Arguments to the component lifecycle hooks of `didInitAttrs`, `didReceiveAttrs`, and `didUpdateAttrs`
+  are deprecated. These arguments were private and undocumented. Please see
+  [RFC #191](https://github.com/emberjs/rfcs/blob/master/text/0191-deprecate-component-lifecycle-hook-args.md)
+  for further context and discussion.
+  Please note that
+  this only deprecates the usage of the arguments passed to this hook, not the
+  hooks themselves. See pull request [#14711](https://github.com/emberjs/ember.js/pull/14711)
+  for additional details.
+
+For more details on the changes in Ember.js 2.12, please review the
+[Ember.js 2.12.0 release page](https://github.com/emberjs/ember.js/releases/tag/v2.12.0).
+
+### Upcoming Changes in Ember.js 2.13
+
+Building on the addition of `factoryFor` in Ember 2.12, Ember 2.13 will change
+the way dependency injection is implemented in the framework. Until 2.12,
+dependencies were injected onto an instance using `extend` to create a subclass.
+This created an excessive number of subclasses during the execution of an
+application. In Ember 2.13 injections will be passed to an object via `create`
+during instantiation. This results in a notable performance improvement
+that grows in impact with the complexity of an application.
+
+See [RFC #150](https://github.com/emberjs/rfcs/blob/master/text/0150-factory-for.md)
+and pull request [#14360](https://github.com/emberjs/ember.js/pull/14360) for
+more details about this change.
+
+Additionally, this release contains a further refinement on the "binary VM"
+change landed in 2.12. By using integers for common Glimmer wire-format strings,
+compiled template sizes in 2.13 will see an incremental size reduction.
+
+In addition to these and other improvements, several changes arising
+from the [RFC](https://github.com/emberjs/rfcs) process have been implemented:
+
+- [RFC issue #146](https://github.com/emberjs/rfcs/issues/146) advocated for the
+  addition of `resumeTest` as a compliment to `pauseTest`. This was implemented
+  in [#13663](https://github.com/emberjs/ember.js/pull/13663).
+- [RFC #186](https://github.com/emberjs/rfcs/blob/master/text/0186-track-unique-history-location-state.md)
+  describes the addition of `uuid` as a property on `HistoryLocation` adapters
+  for the router. This addition makes it possible to track scroll locations
+  to a point in browsing history. See pull request [#14011](https://github.com/emberjs/ember.js/pull/14011)
+  for more details.
+
+For more details on the upcoming changes in Ember.js 2.13, please review the
+[Ember.js 2.13.0-beta.1 release page](https://github.com/emberjs/ember.js/releases/tag/v2.13.0-beta.1).
+
+---
+
+## Ember Data
+
+Ember Data is the official data persistence library for Ember.js applications.
+
+### Changes in Ember Data 2.12
+
+Ember Data 2.12 represents the work of 19 direct contributors
+and over 90 commits.
+
+Ember Data 2.12 continues to reflect our focus on performance improvements, and
+we are happy to report this is the fastest release of Ember Data yet.
+
+A new `serializeId()` method has been added to `JSONSerializer`,
+`RESTSerializer` and `JSONAPISerializer`. This is useful if you are
+working with a backend that requires your ids to be something other
+than a string. For example:
+
+```app/serializers/application.js
+import DS from 'ember-data';
+
+export default DS.JSONSerializer.extend({
+  serializeId(snapshot, json, primaryKey) {
+    var id = snapshot.id;
+    json[primaryKey] = parseInt(id, 10);
+   }
+});
+```
+
+For more information see the [`serializeId` API
+docs](http://emberjs.com/api/data/classes/DS.JSONSerializer.html#method_serializeId).
+
+#### Deprecations in Ember Data 2.12
+
+Ember Data 2.12 contains no new deprecations.
+
+For more details on the changes in Ember Data 2.12, please review the
+[Ember Data 2.12.0 release page](https://github.com/emberjs/data/releases/tag/v2.12.0).
+
+### Upcoming changes in Ember Data 2.13
+
+The `ds-extended-errors` ([#3586](https://github.com/emberjs/data/pull/3586) [#4287](https://github.com/emberjs/data/pull/4287)) feature has been enabled on the beta branch for Ember Data 2.13.
+
+This feature introduces an `extend` method on errors which allows
+users to create their own custom errors that extend from
+`DS.AdapterError`.
+
+```js
+const MyCustomError = DS.AdapterError.extend({ message: "My custom error." });
+```
+
+The feature also introduces some new errors to rest adapter which will
+be used to reject the adapter promises based on http status of the API
+response.
+
+* [401] `DS.UnauthorizedError`
+* [403] `DS.ForbiddenError`
+* [404] `DS.NotFoundError`
+* [409] `DS.ConflictError`
+* [500] `DS.ServerError`
+
+Thanks to [tchak](https://github.com/tchak) and
+[twokul](https://github.com/tchak) for their work on this feature and
+[lindyhopchris](https://github.com/lindyhopchris) for his help
+documenting the feature.
+
+For more details on the upcoming changes in Ember Data 2.13, please review the
+[Ember Data 2.13.0-beta.1 release page](https://github.com/emberjs/data/releases/tag/v2.13.0-beta.1).
+
+---
+
+## Ember CLI
+
+Ember CLI is the command line interface for managing and packaging Ember.js
+applications.
+
+### Upgrading Ember CLI
+
+You may upgrade Ember CLI separately from Ember.js and Ember Data! To upgrade
+your projects using `yarn` run:
+
+```
+yarn upgrade ember-cli
+```
+
+To upgrade your projects using `npm` run:
+
+```
+npm install --save-dev ember-cli
+```
+
+After running the
+upgrade command run `ember init` inside of the project directory to apply the
+blueprint changes. You can preview those changes for [applications](https://github.com/ember-cli/ember-new-output/compare/v2.11.0...v2.12.0)
+and [addons](https://github.com/ember-cli/ember-addon-output/compare/v2.11.0...v2.12.0).
+
+### Changes in Ember CLI 2.12
+
+#### Switch to ESLint
+
+Ember CLI will now generate new projects with an ESLint setup. This changes the default linting system from JSHint (which has been used
+since we initially added linting support to ember-cli) to ESLint. The new project setup uses a fairly simple `.eslinrc.js` relying
+largely on ESLint's own `recommended`.
+
+Using JSHint in projects and addons generated by prior versions of ember-cli is still supported, but we recommend that you update to
+ESLint as you upgrade your project and addons to newer ember-cli versions.
+
+#### Reduced Dependencies
+
+In order to avoid inconsistencies and issues due to supporting many `npm` client versions, Ember CLI has had `npm` as a dependency
+for quite some time. This is used for both `ember new foo` (to initially install dependencies for a newly generated application) and
+to install packages via `ember install ember-cli-template-lint` (to install the addon specified). Having `npm` as a dependency
+introduces roughly 19MB to a freshly generated ember-cli application's `node_modules` size. As the `npm` client has become more stable (3.x series and
+newer) this has seemed more and more wasteful.
+
+Starting with Ember CLI 2.12, `npm` is no longer a dependency of ember-cli. If a suitable version of `npm` is present on the system,
+it will be used. If either `npm` is not found or a version older than `3.0.0` is found, ember-cli will emit an error when you run commands that would utilize
+`npm` (e.g. `ember install`, `ember new`, `ember addon`, `ember init`).
+
+Similarly, Ember CLI had a dependency on `bower` in order to support the `bower install` phase while generating new projects and installing
+addons.
+As of Ember CLI 2.11 a new application has no dependencies via `bower.json`. This means the dependency on `bower` itself is also potential bloat.
+Having `bower`
+as a dependency added roughly 21MB to a new application's total `node_modules` size. In Ember CLI 2.12, bower is only added as a dependency if a command
+requires `bower` and it is not already installed globally.
+
+Combined, these changes result in approximately 40MB of reduction in `node_modules` size on a newly generated application.
+
+#### Other Notable Changes
+
+* `ember-data` has been removed from the addon blueprint.
+* Properly call `preprocessTree` / `postprocessTree` for addons.
+* Split serving assets into separate internal addons. This enables work to push ember-cli-fastboot towards 1.0.0.
+
+For more details on the changes in Ember CLI 2.12 and detailed upgrade
+instructions, please review the [Ember CLI 2.12.0 release page](https://github.com/ember-cli/ember-cli/releases/tag/v2.12.0).
+
+### Upcoming Changes in Ember CLI 2.13
+
+#### Add support for using `yarn`
+
+Ember CLI projects have been able to utilize `yarn` for dependency management for quite some time, however it was not well supported by
+the default generators. In 2.13 Ember CLI is now "yarn aware", and will use `yarn` for tasks such as `ember install` if it detects that
+`yarn` is installed and a `yarn.lock` exists in the project. You can even instruct `ember new` to generate a new project with a `yarn.lock`
+for you via `ember new foo --yarn`.
+
+#### Enable Instrumentation Hooks
+
+Ember CLI has had the ability to generate custom instrumentation output for builds for a few years now (introduced on 2015-08-24), but
+this information has not been readily accessible. In 2.13 ember-cli exposes this information to addons that implement the `instrumentation`
+hook. This allows addons to access many things that were previously very difficult (e.g. reliable build time reporting).
+
+Thanks to [@hjdivad](https://github.com/hjdivad) for proposing and implementing this feature. Please read through [the RFC](https://github.com/ember-cli/rfcs/blob/master/complete/0091-addon-instrumentation-experimental-hooks.md)
+for more details.
+
+#### Target
+
+In order to allow addons to understand the desired target platforms of the app that they are operating in, a new file has been added
+to all generated projects: `config/targets.js`. This file exposes the supported targets so that tooling such as [autoprefixer](https://github.com/postcss/autoprefixer) 
+and [babel-preset-env](https://github.com/babel/babel-preset-env) can properly understand the level of transpilation that is needed.
+
+The default `config/targets.js` looks like:
+
+```js
+module.exports = {
+  browsers: [
+    'ie 9',
+    'last 1 Chrome versions',
+    'last 1 Firefox versions',
+    'last 1 Safari versions'
+  ]
+};
+```
+
+The target information is exposed to addons via `this.project.targets`.
+
+Thanks to [@cibernox](https://github.com/cibernox) for proposing and implementing this feature. Please read through [the RFC](https://github.com/ember-cli/rfcs/blob/master/complete/0095-standardise-targets.md)
+for more insight.
+
+#### Babel 6
+
+Babel 6 was introduced on stage during EmberCamp London way back on 2015-10-29, however ember-cli and the entire ember-cli ecosystem
+has continued to use the aging and nearly unsupported Babel 5. Babel 6 was a massive shift for Babel and the migration posed quite a
+challenge for ember-cli.
+
+After much work Babel 6 support has been added to ember-cli internally and for newly generated projects (both applications and addons).
+The latest beta of ember-cli-babel@6 takes advantage of the new `project.targets` API along with [babel-preset-env](https://github.com/babel/babel-preset-env)
+to allow applications to have significantly better control of exactly what is transpiled. `babel-preset-env` utilizes the [caniuse](http://caniuse.com/) and
+[@kangax]'s [ES6 compatibility database](https://kangax.github.io/compat-table/es6/) to know which features are available natively and which
+require transpilation. For example, with the proper targets configuration ember-cli-babel will no longer transpile `const` / `let`, 
+`() => { }` functions, `class`, etc.
+
+The work done in ember-cli-babel allows both ember-cli-babel@5 and ember-cli-babel@6 to coexist peacefully, so it is safe for addon authors
+to begin updating their internal ember-cli-babel dependency so that applications can take advantage of more of these babel@6 features.
+
+Please test your applications and addons with ember-cli-babel@6 and report any issues you encounter. Due to the large number of changes required 
+internally, we would like a larger than normal beta testing base to ensure things are as stable as possible before 2.13.0 is released.
+
+#### Other Notable Changes
+
+* `bower.json` is no longer included in a newly generated project.
+* Fix command interruption issues on windows.
+* Added `filesToRemove` property for custom blueprints.
+
+For more details on the changes in Ember CLI 2.13.0-beta.1 and detailed upgrade
+instructions, please review the [Ember CLI 2.13.0-beta.1 release page](https://github.com/ember-cli/ember-cli/releases/tag/v2.13.0-beta.1).
+
+## Thank You!
+
+As a community-driven open-source project with an ambitious scope, each of
+these releases serve as a reminder that the Ember project would not have been
+possible without your continued support. We are extremely grateful to our
+contributors for their efforts.