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?
- 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.toStringthat 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.
getRecommendedTimeoutMillisAPI 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
You can follow along or contribute to our outstanding accessibility issues here!
Notable Dependency Version Updates and Gotchas
0.0.7is now needed as a
- 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.
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.