Today we’re releasing React Native 0.64 that ships with support for Hermes on iOS.

Hermes opt-in on iOS​

Hermes is an open source JavaScript engine optimized for running React Native. It improves performance by decreasing memory utilization, reducing download size and decreasing the time it takes for the app to become usable or “time to interactive” (TTI).

With this release, we are happy to announce that you can now use Hermes to build on iOS as well. To enable Hermes on iOS, set hermes_enabled to true in your Podfile and run pod install .

use_react_native!(
   :path => config[:reactNativePath],
   # to enable hermes on iOS, change `false` to `true` and then install pods
   :hermes_enabled => true
)

Please keep in mind that Hermes support on iOS is still early stage. We are keeping it as an opt-in as we are running further benchmarking. We encourage you to try it on your own applications and let us know how it is working out for you!

Inline Requires enabled by default​

Inline Requires is a Metro configuration option that improves startup time by delaying execution of JavaScript modules until they are used, instead of at startup.

This feature has existed and been recommended for a few years as an opt-in configuration option, listed in the Performance section of our documentation. We are now enabling this option by default for new applications to help people have fast React Native applications without extra configuration.

Inline Requires is a Babel transform that takes module imports and converts them to be inline. As an example, Inline Requires transforms this module import call from being at the top of the file to where it is used.

Before:

import {MyFunction} from 'my-module';

const MyComponent = props => {
  const result = MyFunction();

  return <Text>{result}</Text>;
};

After:

const MyComponent = props => {
  const result = require('my-module').MyFunction();

  return <Text>{result}</Text>;
};

More information about Inline Requires is available in the Performance documentation.

View Hermes traces with Chrome​

Over the last year Facebook has sponsored the Major League Hacking fellowship, supporting contributions to React Native. Jessie Nguyen and Saphal Patro added the ability to use the Performance tab on Chrome DevTools to visualize the execution of your application when it is using Hermes.

For more information, check out the new documentation page.

Hermes with Proxy Support​

We have added Proxy support to Hermes, enabling compatibility with popular community projects like react-native-firebase and mobx. If you have been using these packages you can now migrate to Hermes for your project.

We plan to make Hermes the default JavaScript engine for Android in a coming release so we are working to resolve the remaining issues people have when using Hermes. Please open an issue on the Hermes GitHub repo if there are remaining issues holding back your app from adopting Hermes.

React 17​

React 17 does not include new developer-facing features or major breaking changes. For React Native applications, the main change is a new JSX transform enabling files to no longer need to import React to be able to use JSX.

More information about React 17 is available on the React blog.

Major Dependency Version Changes​

• Dropped Android API levels 16-20. The Facebook app consistently drops support for Android versions with sufficiently low usage. As the Facebook app no longer supports these versions and is React Native’s main testing surface, React Native is dropping support as well.
• Xcode 12 and CocoaPods 1.10 are required
• Minimum Node support bumped from 10 to Node 12
• Flipper bumped to 0.75.1

Thanks​

Thank you to the hundreds of contributors that helped make 0.64 possible! The 0.64 changelog includes all of the changes included in this release.

It has been four weeks since we reached out to the GitHub community with a thoroughly reviewed gap analysis and list of issues to improve React Native's accessibility. With the help of the React Native community, we are already making great progress on improving accessibility. Community members have been helping contributors, reviewing tests, and bringing attention to prior accessibility issues. Since March 8th the community has closed six issues with four pull requests and seven other pull requests are in the pipeline for review.

While this work continues, the React Native and Accessibility teams at Facebook are evaluating accessibility bugs and issues that were submitted prior to this initiative, to determine if they are already covered by our current gap analysis or if there are additional issues that need to be brought into the project. One new issue has already been discovered and moved into the project, four others directly mapped to existing issues and two others are expected to be closed by addressing existing issues that address the root cause of their issue.

Thank you to all the community members who have participated. You are truly moving the needle in making React Native more accessible for everyone!

Closed Pull Requests 🎉​

• Added talkback support for button accessibility: disabled prop #31001 - closed by @huzaifaaak

• feat: set disabled accessibilityState when TouchableHighlight is disabled #31135 closed by @natural_clar

• [Android] Selected State does not annonce when TextInput Component selected #31144 closed by fabriziobertoglio1987

• Added talkback support for TouchableNativeFeedback accessibility: disabled prop #31224 closed by @kyamashiro73

• Accessibility/button test #31189 closed by @huzaifaaak

  • Adds a test for accessibilityState for button

Fixes​

• Button component (fixed by #31001):

  • Now announces when it is disabled

  • Disables click functionality for screen readers when the button is disabled

  • Announces the selected state of the button

• TextInput component (fixed by #31144):

  • Announces "selected" when the "selected" accessibilityState is set to true and the element is focused

• TouchableHighlight component (fixed by #31135):

  • Disables click functionality for screen readers when the component is disabled

• TouchableNativeFeedback component (fixed by #31224):

  • Disables click functionality for screen readers when the component is disabled

Other Progress​

Get involved!​

• New contributors should read the contribution guide and browse the list of 37 good first issues in the React Native GitHub.

• Contributors interested in issues requiring a bit more effort should visit the project page for Improved React Native Accessibility to see the GitHub issues that need their knowledge of React Native.

• Technical writers interested in updating React Native's documentation to reflect the accessibility gaps being closed should visit the React Native Docs.

• Share this initiative with anyone who may be able to help!

• Follow the GAAD Pledge Open Source Accessibility Community Manager for React Native on Twitter or Facebook to keep up to date on progress.

It has been one year since Facebook took the GAAD Pledge to make React Native accessible and the project has exceeded our expectations. We are excited to announce that this project will continue throughout 2021 and want to update everyone on our progress so far. Following a thorough analysis of the accessibility gaps in React Native last year, work began on filling these gaps.

We started with 90 outstanding gap analysis issues and from March 2021, when the project launched on GitHub, until now:

• 11 issues have been closed by the community.

• 19 issues were evaluated and closed by the React Native team.

• 9 pull requests were merged.

• 1 pull request was merged into the React Native docs.

We want to recognize and thank the React Native community for the significant progress towards a more accessible React Native over the past year. Every contributor's effort has counted in making progress on improving React Native Accessibility.

Fixes​

Two types of issues have been fixed in multiple components and one new functionality has been added to the API by the 9 pull requests.

• An issue with Disabled state has been addressed in seven components

• An issue with Selected state was addressed in two components

• A new addition to the React Native API added the ability to query AccessibilityManager.getRecommendedTimeoutMillis().

Disabled State Announcement and Disable function​

One of the most prevalent issues found during the gap analysis was that some components do not announce or disable functionality. Now seven components announce their disabled state or disable click functionality.

Announces when Disabled

• Button - #31001

• Images - #31252

• ImageBackground - #31252

Disables click functionality when the component has a disabled prop

• Button - #31001

• Text - React Native Team commit

• Pressable - React Native Team commit

• TouchableHighlight - #31135

• TouchableOpacity - #31108

• TouchableNativeFeedback - #31224

• TouchableWithoutFeedback - #31297

Selected State Announcement​

There were some components that did not announce their selection when in focus. This behavior has now been fixed when the component is in focus and the AccessibilityState is set to selected or the component is changed to selected.

Announces when Selected

• Button - #31001

• TextInput - #31144

Accessibility Timeout Setting​

There was previously no way to query the accessibility timeout setting on Android. The fix added the ability to query AccessibilityManager.getRecommendedTimeoutMillis() . This queries the "Time to take action" before the UI elements auto-dismisses or auto-progresses.

Documentation Additions​

The React Native documentation must be updated to reflect each addition or change to the available APIs. The new addition to the React Native documentation covered the addition of getRecommendedTimeoutMillis() to AccessibilityInfo.

Community Involvement​

We want to thank all the contributors mentioned below who have submitted and merged pull requests as well as those who have reviewed and commented on issues.

Merged Pull Requests​

• @huzaifaaak closed 3 issues with:
  • Added talkback support for button accessibility: disabled prop #31001
  • Accessibility/button test #31189
• @natural_clar closed 1 issue with:
  • feat: set disabled accessibilityState when TouchableHighlight is disabled #31135
• fabriziobertoglio1987 closed 2 issues with:
  • [Android] Selected State does not annonce when TextInput Component selected #31144
  • Accessibility Fix Image does not announce "disabled" #31252
• @kyamashiro73 closed 1 issue with:
  • Added talkback support for TouchableNativeFeedback accessibility: disabled prop #31224
• @grgr-dkrk closed 1 issue and added to the React Native documentation with:
  • add getRecommendedTimeoutMillis to AccessibilityInfo #31063
  • feat: add getRecommendedTimeoutMillis section on accessibilityInfo #2581
• @crloscuesta closed 1 issue with:
  • Disable accessibilityState when TouchableWithoutFeedback is disabled #31297
• @chakrihacker closed 1 issue with:
  • Disable TouchableOpacity when accessibility disabled is set #31108

Thank you to the community members who gave their time in other ways!

Simek, saurabhkacholiya, meehawk, intergalacticspacehighway, chrisglein, jychiao and Waltari10

Get Involved!​

We've come a long way but we're not done yet. We need your support to reach the finish line. Facebook's React Native team has committed to supporting contributors working on gap analysis issues. They will continue to respond to comments on Accessibility issues and triage pull requests. The React Native team is also tackling some of the toughest gap analysis issues. This work includes the correct translation of accessibilityRoles to other languages and specifying error text for specific components.

Join us in tackling the rest. There are still open accessibility issues on the Improved React Native Accessibility project board. Issues with Checked/Unchecked State, Entrance/exit from Collection, and Position in Collection are great opportunities for current and new contributors to contribute to a more accessible React Native.

Learn More​

Read about how the gap analysis was conducted on the Facebook Tech blog or about the launch of the GitHub issues on the React Native Blog.

Today we’re releasing React Native version 0.65 with a new version of Hermes, improvements to accessibility, package upgrades, and more.

What's new in Hermes 0.8?​

Hermes, Facebook’s open source JavaScript VM optimized for React Native, has been upgraded to version 0.8.1. Some of the stand-out features in this release are:

• A new concurrent garbage collector titled “Hades” which delivers up to 30 times shorter pause times on 64 bit devices. At Facebook, we saw this improve some CPU-intensive workloads by 20%-50%. You can learn more about Hades here.
• ECMAScript Internationalization API (ECMA-402, or Intl ) is now built into Hermes on Android and enabled by default, with only 57-62K per API size overhead (compared to JSC's 6MiB). With this change, Hermes users no longer require locale polyfills. A big thank you to @mganandraj and other partners at Microsoft for driving the implementation to make this happen!
• Hermes on iOS now supports Apple M1 Macs and Mac Catalyst!
• Memory improvements including SMI (Small Integers) and pointer compression that shrank JS heap by 30%.
• Changes to Function.prototype.toString that fixed a performance drop due to improper feature detection and supports the source code injecting use case.

You can find the full Hermes changelog here.

Follow steps here to opt-in your app to Hermes if you haven’t already to leverage these new features and gains!

Accessibility Fixes and Additions​

Last year Facebook took the GAAD pledge to improve accessibility within React Native. 0.65 shares the results of this pledge and other accessibility wins! Some notable changes include:

• Allow specification of high contrast light and dark values for iOS. See documentation for more details.
• Added getRecommendedTimeoutMillis API on Android. This exposes a user’s preferred default timeout value as set in Android’s accessibility options and is for users who may need extra time to review or reach controls, etc.
• General fixes to ensure TalkBack/VoiceOver properly announce UI states such as disabled and unselected on components.

You can follow along or contribute to our outstanding accessibility issues here!

Notable Dependency Version Updates and Gotchas​

• react-native-codegen version 0.0.7 is now needed as a devDependency in the package.json .
• JCenter has been sunsetted and read-only now. We have removed JCenter as a maven repository and updated dependencies to use MavenCentral and Jitpack.
• Upgraded OkHttp from v3 to v4.9.1. See Upgrading to OkHttp 4 for more details on changes.
• Upgraded to Flipper 0.93 to support Xcode 12.5. See Flipper changelog here.
• Android Gradle Plugin 7 support
• Apple Silicon requires a linker workaround. See @mikehardy’s note about this.

Thank You!​

This release includes over 1100 commits from 61 contributors . Thank you to everyone who has contributed and supported this release! You can find the full changelog here.

Over the past year so much has changed in our world, React Native being no exception. We've welcomed new members to our team (whom we are excited to eventually meet in person!), our projects have matured and new opportunities have arisen. We're excited to share all this with you in this post and others to come!

At Facebook, our team works in half-year cycles. Each half we review our strategy, set plans, and share them internally. Today, we want to share our H2 plans with you, our community.

H2 2021 is an exciting half for React Native. Our areas of focus include nurturing the community, beginning to roll out the new architecture to open source, and pushing the technology forward.

Setting up the Community for Success​

React Native’s open source ecosystem is one of its greatest strengths. We’ve identified the following areas as the best ways to grow our partnership with the community.

Community Engagement​

In order for everyone to move in the same direction, we want to continually communicate our vision and status to the community. Sharing our incremental progress publicly isn’t second-nature for us (yet). This half, we are committing to a more consistent content schedule that exercises the muscle and sets up processes to reduce friction. Beyond sharing our updates, we also want to use this opportunity to showcase the accomplishments of the community.

New Architecture Rollout and Releases​

In H1, we finished rolling out the new React Native architecture to all React Native mobile products in the Facebook app. Facebook is made up of surfaces like Marketplace Tab and Dating Profile, and we have migrated over 1000 surfaces!

In H2, we are beginning to bring this new architecture to the community. We have put together a playbook that shows how to migrate libraries and applications. We have already shared drafts with early partners that maintain popular React Native libraries. We expect to get their feedback, support them in upgrading their libraries, and learn how to improve our playbook and implementations. We plan on sharing the playbook more broadly as soon as the work stabilizes.

We are also focused on improving React Native’s release process. We will need frequent reliable releases to progressively ship the new React Native architecture. Our aim is to catch release-blockers earlier and to reduce the turn-around time. This will enable more predictable release timelines with less burden on contributors and developers.

Repository Health​

When developers evaluate a technology, an essential signal is the health of its repository. This impression is informed by signals such as pull request throughput, stars, age of last commit, and others. The React Native repository has historically lacked a process to ensure that issues and pull requests are reviewed in a timely manner. Our work this half is two-fold: we need to resolve a large backlog of contributions, and we need to build sustainable practices for handling incoming contributions. We hope this work will also set us up for success for more engagement from the community via issues and PRs as the community starts using the new architecture. You can follow our progress on the backlog using this project board.

Pushing the Technology Forward​

New Architectural Capabilities​

As mentioned, our new architecture recently finished rolling out to the Facebook mobile apps! We are already building new capabilities that will change the performance curve for React Native. This includes supporting Concurrent Rendering in React Native. Concurrent Rendering enables React to pause and resume work and quickly respond to high priority events like a touch gesture. Something we are also really excited about is using Concurrent Rendering to make use of idle CPU cycles for rendering offscreen product features without slowing down onscreen user interactions.

Mobile and Beyond​

We have had overwhelming success with powering mobile experiences using React at Facebook, and we have seen amazing mobile products from our partners. Now we want to bring that success to more platforms! We believe that targeting many platforms lets us learn new lessons and further improve our offering on mobile platforms. (We will share more about this in a later post.) The exciting news is that we’ve already started taking steps towards making this a reality!

Messenger Desktop​

Last summer, we expanded our focus beyond mobile by partnering with Microsoft to accelerate React Native development on Windows and macOS. We partnered with the Messenger team at Facebook to enable user experiences that are only possible on desktop, and to deliver huge performance wins over their previous Electron implementation. Our vision is to combine high quality, delightful, native desktop user experiences with the great developer experience of React Native.

The Messenger team has ambitious plans for the Messenger desktop apps, including finding new ways to further unleash the unique capabilities of desktop platforms and large screens. We are excited to continue enabling these experiences by investing more into React Native on desktop.

React Native in Virtual Reality​

Oculus has long used React Native to power core experiences like Store, where people buy applications and games in VR. In H2, React Native and Oculus are partnering to bring new exciting experiences to VR. We are also bringing optimizations and improvements from VR to mobile, and from mobile to VR. This will include expanding React Native to support unique requirements of VR — from new input types like controllers to new memory usage optimizations. This is the start of an exciting journey to explore and influence how immersive experiences can built for VR using React Native.

Summary​

We hope our H2 plans excite you as much as it does us, and we look forward to sharing more with you in the upcoming months! We will also be attending React Native EU on September 1, 2021 where teammate Joshua Gross (@joshuaisgross) will share how we replaced the architecture for the world’s largest React Native app. Register for React Native EU if you haven’t already! In the meantime, connect with us on Twitter (@reactnative) for updates on events, our roadmap, and much more.