facebook / hermes
✓ Official★ 11,200A skill package that teaches your agent 4 capabilities — every one documented and browsable below, no GitHub required · by facebook.
Each skill below is one capability this package teaches your agent. Install the whole package, or open a skill to install just that one.
When adding a new IR instruction, you must touch a specific set of files. This skill describes each file, the pattern to follow, and important conventions.
1 file — installable on its own
Analyze per-commit binary size changes of the hermesvm shared library across a git commit range. Produces a markdown report with per-commit sizes and summary tables of significant increases and decreases.
1 file — installable on its own
For the full explanation and rationale, see doc/GCSafeCoding.md .
1 file — installable on its own
Use when needing to reorder, split, drop, or amend git commits that are not the top commit, without interactive editor access. Covers programmatic rebase via…
1 file — installable on its own
Hermes JS Engine
<img src="./doc/img/logo.svg" alt="Hermes logo - large H with wings" align="right" width="20%"/>
Hermes is a JavaScript engine optimized for fast start-up of React Native apps. It features ahead-of-time static optimization and compact bytecode.
If you're only interested in using pre-built Hermes in a new or existing React Native app, you do not need to follow this guide or have direct access to the Hermes source. Instead, just follow these instructions to enable Hermes.
Noted that each Hermes release is aimed at a specific RN version. The rule of thumb is to always follow Hermes releases strictly. Version mismatch can result in instant crash of your apps in the worst case scenario.
If you want to know how to build and hack on Hermes directly, and/or integrate Hermes built from source into a React Native app then read on.
Hermes Blog - Technical articles and deep dives into Hermes internals.
The instructions here very briefly cover steps to build the Hermes CLI. They assume you have typical native development tools setup for your OS, and support for cmake and Ninja. For more details of required dependencies, building Hermes with different options, etc. follow these links instead:
To build a local debug version of the Hermes CLI tools the following steps should get you started on macOS/Linux:
mkdir hermes_workingdir
cd hermes_workingdir
git clone https://github.com/facebook/hermes.git
cmake -S hermes -B build -G Ninja -DCMAKE_BUILD_TYPE=Debug
cmake --build ./buildOr if you're using Windows, the following should get you going in a Git Bash shell:
mkdir hermes_workingdir
cd hermes_workingdir
git -c core.autocrlf=false clone https://github.com/facebook/hermes.git
cmake -S hermes -B build -G 'Visual Studio 16 2019' -A x64
cmake --build ./buildYou will now be in a directory with the output of building Hermes into CLI tools. From here you can run a piece of JavaScript as follows:
echo "'use strict'; function hello() { print('Hello World'); } hello();" | ./bin/hermesContributing
The main purpose of this repository is to continue to evolve Hermes, making it faster and more efficient. We are grateful to the community for contributing bugfixes and improvements. Read below to learn how you can take part in improving Hermes.
Code of Conduct
Facebook has adopted a Code of Conduct that we expect project participants to adhere to. Please read the full text so that you can understand what actions will and will not be tolerated.
Contributing Guide
Read our contributing guide to learn about our development process, how to propose bugfixes and improvements, and how to build and test your changes to Hermes.
License
Hermes is MIT licensed.
Install the whole package (4 skills):
npx skills add https://github.com/facebook/hermesOr install a single skill:
npx skills add https://github.com/facebook/hermes --skill <name>Pick the skill name from the Skills tab — each entry there installs independently.