hermes

This release corresponds to RN 0.75.

This release comes with many bug fixes, language features (WeakRef & BigInt), and also the removal of the debugger on the command line tools. This means much better performance when using Hermes from the CLI. In addition, RN now builds Hermes from source, so we no longer need to publish specific versions of Hermes to target a specific version of RN.

In preparation for the 0.68.x, this release brings numerous bug fixes and performance improvements to Hermes.

In preparation for the release of RN0.67, this release brings numerous bug fixes and performance improvements to Hermes.

This release is primarily made to close the gap between the Hermes cut and the (upcoming) React Native 0.66 cut. Among the ~400 commits, we kept delivering memory and size wins, bugfixes, and made other progress behind the scene.

In preparation for the RN 0.65 stable release, several refinements had been made upon v0.8.0:

• Hermes on iOS now supports Apple M1 Macs (ARM64 simulators) and Mac Catalyst! Thanks to https://github.com/facebook/hermes/pull/546 and https://github.com/facebook/hermes/pull/475.
• A special directive "show source" is introduced to make Function.prototype.toString returning original source code to support the source code injecting use cases e.g. https://github.com/facebook/hermes/issues/114.
• Critical bug fixes e.g. https://github.com/facebook/hermes/issues/513 and https://github.com/facebook/hermes/issues/537.

This is a release candidate targeting the upcoming RN 0.65 release.

Highlighted Changes

• A new concurrent garbage collector "Hades", which delivered up to 30x shorter GC pause time on 64-bit device and 14x shorter on 32-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 Specification (ECMA-402, or Intl) was a long asking features https://github.com/facebook/hermes/issues/23#issuecomment-816126715. It 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!
• Memory Improvements including SMI (Small Integer) and pointer compression that shrank the JavaScript heap by 30%
• Changes to Function.prototype.toString that fixed performance drop due to improper feature detection: https://github.com/facebook/hermes/issues/471#issuecomment-820123463

This release includes miscellaneous fixes to support the road to RN 0.64.

This release is to add the latest macOS ARM64 support to 0.4.x branch for RN macOS v0.62.x (@alloy in https://github.com/facebook/hermes/pull/351).

This release adds macOS ARM64 support to 0.5.x branch for RN macOS v0.63.x (https://github.com/facebook/hermes/pull/390 by @alloy).

NOTE: this release is only available for the Darwin platform (i.e. this version only exists at hermes-engine-darwin but not hermes-engine). Please use 0.5.1 or 0.5.2-rc1 (with Proxy enabled) for other platforms.

This is (still) a pre-release driven by community PRs to support using Hermes on more platforms at RN 0.64. Noted that ongoing from this release, we will publish hermes-runtime-darwin to the CocoaPod in place of publishing hermes-engine-darwin to NPM.

This is a pre-release targeting the upcoming RN 0.64 branch out. It bring ~150 commits of improvements, security and bug fixes, and supports for other mobile platforms and ARM64 thanks to the community.

From this version, Proxy and Reflect will be enabled by default 🎉 , after being an optional feature in two releases.

This release brings ~350 commits worth of bugfixes and improvements, and is aimed at the upcoming 0.64 branch of React Native.

Among them are correctness and performance fixes in regex, parsing improvements and native support for more JS features, a JS memory leak fix, and a new NPM that aims to help build React Native apps that target macOS instead of mobile. It also includes everything from patch release v0.5.1, notably, the unstripped Android libraries to help with native debugging and symbolication.

This release is a drop-in replacement for v0.5.0 and v0.5.1 in react-native 0.63.x with Proxy and Reflect enabled by default. It's the follow-up of v0.4.2-rc1 on opting-in Proxy support (https://github.com/facebook/hermes/issues/33).

To help with debugging crashes that observed on v0.4.2-rc1, we are now shipping unstripped Android libraries as well. You can now following the new instruction to better report such native crashes.

Please let us know your experiences! We need your help to move the Proxy into the stable channel!

EDIT: From the feedbacks at https://github.com/facebook/hermes/issues/33, 0.5.2-rc1 seem to be stable enough. Noted that (thanks for the discussion at https://github.com/facebook/hermes/issues/459) there isn't another stable release made for 0.5.x lines with Proxy enabled. We've enabled Proxy by default at 0.7.0 for RN 0.64 and people at RN 0.63 wanting Proxy can directly use [email protected].

This release is primarily for building artifacts for React Native for macOS (@alloy in #299). It also Includes the missing vcruntime140_1.dll on Windows, negating the need to install VC++ redistributables separately (@willholen in #310).

Two more artifacts, namely hermes-runtime-darwin and hermes-engine-darwin (a wrapper of the former meant to be consumed by npm), will be included in the release assets from now on.

Following the discussion at https://github.com/facebook/hermes/issues/243, this release includes several parsing bugfixes (e.g. #219, #235, #241) and improves debugging experiences. Notably, starting from v0.5.1, unstripped Android libraries are provided in the attached artifacts to help with native debugging and symbolication. It's a drop-in replacement for v0.5.0 in react-native 0.63.x.

Among the 200+ commits in this release, the most user visible change is the NPM size reduction from 140MB to 18MB unpacked. This will lead to snappier npm installs and project creation.

We're also publishing the new NPM hermes-engine-cli containing several host platform CLI tools for testing and development purposes, including a debugger and bytecode disassembler.

This release fixes a memory leak related to WeakMaps. It's a drop-in replacement for v0.4.0 in react-native 0.62.0.

This release includes an implementation of Proxy and Reflect, but it is not enabled by default. To enable it for the command line tools, pass the -Xes6-proxy flag, such as hermes -Xes6-proxy. Proxy will be enabled in a future release of React Native.

The 0.4.0 release is not compatible with RN 0.61.

This release also includes a number of other performance enhancements, bug fixes, and memory savings in the engine.

This release is primarily to publish breaking source changes for integration with the next version of React Native. It is not compatible with existing builds of React Native, up to and including 0.61.4. Please wait for the next React Native release before trying out Hermes v0.3.0!

As always there are many bug fixes and performance improvements, including faster string concatenation and native support for ES6 spread operators.