Ember 4.5 Released

– By Jen Weber, Chris Krycho

Today the Ember project is releasing version 4.5 of Ember.js and Ember CLI.

Version 4.4 of Ember is now promoted to LTS (Long Term Support). An LTS version of Ember continues to receive security updates for 9 release cycles (54 weeks) and bugfixes for 6 cycles (36 weeks). LTS releases typically occur every four minor versions. The previous LTS version of Ember was 3.28.

This release kicks off the 4.5 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 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:


Ember.js is the core framework for building ambitious web applications.

Changes in Ember.js 4.5

Ember.js 4.5 is an incremental, backwards compatible release of Ember with bug fixes, performance improvements, and minor deprecations.

Bug Fixes

Ember.js 4.5 introduced 0 bug fixes.


Ember.js 4.5 introduced 2 new features.

  1. Plain function as helpers
  2. A new renderSettled test helper
1. Plain functions as helpers

You can now use plain functions as helpers in your component templates. This helps make the relationship between Ember component templates and their JavaScript class more intuitive.

For example, here we create a method double and use it directly in a template:

// my-component.js

import Component from '@glimmer/component';

export default class MyComponent extends Component {
  double = num => num * 2;
// my-component.hbs

{{this.double 2}}

<SomeComponent @foo={{this.double 2}} />

Previously, you could define this locally, but still had to use the helper() function to accomplish this.

We're working on updating the Guides to cover this pattern. For background, check out RFC 756, which designed this feature. Also, keep your eyes on this blog: we will have a dedicated blog post with a deep dive on this new capability in the next week or two!

2. A new renderSettled test helper

Under the hood, Ember's tests use a "test waiters" system to allow you to control the flow of your tests in terms of the actual framework behavior. That way that your tests match exactly what the app does at runtime.

However, making this work depends on Ember providing all the necessary hooks for test helpers to use, and there was one significant missing public API. You could wait for all of the test waiters to finish with settled, but there was no public way to wait for just rendering to finish. For example, you might want to wait for rendering to finish but not for an Ember Data save operation to finish, as part of testing a loading screen.

Ember 4.5 introduces a new function, renderSettled, as a public way for test helpers to interact with the rendering phase of the application. renderSettled returns returns a promise which fulfills as soon as rendering has completed. It can be used in any rendering or application test. (It also works in other tests where you set up the rendering hooks manually, but this is unusual!)

import { renderSettled } from '@ember/renderer';

An recent release of @ember/test-helpers, v2.8.0, takes advantage of this to provide a new await rerender() helper. For more details, and how this fits into improvements to Ember's testing story, see RFC 785.


Ember.js 4.5 introduced 0 deprecations.

For more details on changes in Ember.js 4.5, please review the Ember.js 4.5.0 release page.

Ember Data

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

Due to low availability for the Ember Data team this cycle, Ember Data does not have a new release, so it remains at 4.4.

Please see the Ember 4.4 release blog post for details about v4.4 of Ember Data.

Ember CLI

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

Upgrading Ember CLI

You may upgrade Ember CLI using the ember-cli-update project:

npx ember-cli-update

This utility will help you to update your app or addon to the latest Ember CLI version. You will probably encounter merge conflicts, in which the default behavior is to let you resolve conflicts on your own. For more information on the ember-cli-update project, see the GitHub README.

While it is recommended to keep Ember CLI versions in sync with Ember and Ember Data, this is not required. After updating ember-cli, you can keep your current version(s) of Ember or Ember Data by editing package.json to revert the changes to the lines containing ember-source and ember-data.

Changes in Ember CLI 4.5

Bug Fixes

Ember CLI 4.5 introduced a variety of small bug fixes and documentation improvements. You can find the full list in the Ember CLI 4.5.0 release page.


Ember CLI 4.5 introduced 0 features.


Ember CLI 4.5 introduced 2 deprecations.

  • Using the terms whitelist and blacklist build options are deprecated. Please use include and exclude instead. Only the name of the option has changed, and the functionality is unchanged. This work to add the new option naming was initially planned in RFC 639, and the deprecation RFC is RFC 801.
  • Support for ember-cli-jshint is deprecated.

The addonJsFiles method that was previously deprecated in v3.13 of Ember CLI has now been removed.

For more details on the changes in Ember CLI 4.5 and detailed upgrade instructions, please review the Ember CLI 4.5.0 release page.

Thank You!

As a community-driven open-source project with an ambitious scope, each of these releases serves 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.