Multithreaded React Native code running in a browser via WebAssembly

综合技术 2018-05-18 阅读原文

React Native DOM ·

An experimental, comprehensive port of React Native to the web.

  • Multithreaded by default:
    Following the exact same architecture as React Native on mobile, all of your react components/app logic are run in web worker, leaving the main thread to entirely focus on rendering.
  • Same layout behavior as React Native on mobile:
    Powered by custom bindings to Yoga and compiled to Web Assembly, avoid layout inconsistencies between your native and web projects.
  • Built with the same bundler used for existing React Native platforms:
    Build both the "native" main and JS threads with the Metro Bundler along with all the developer experience features it provides.
  • Ecosystem compatible escape hatch to the DOM:
    Using the same native module bridge, expose DOM-specific APIs in a more generic way that can easily be made into a cross-platform module.

To see it in action, check out these live demos:


This project is still highly experimental and many aspects of it are subject to
breaking changes, continue at your own risk.

Getting Started

Getting your React Native project configured to use react-native-dom
is a lot
like the process for other 3rd party platforms such as react-native-windows

If you're starting a new project from scratch: ensure you have the react-native
CLI installed globally.

npm install -g react-native-cli
# or
yarn global add react-native-cli

Next, initialize your React Native project.

react-native init [project name]

Then, cd
into your project and install rnpm-plugin-dom
into your devDependencies
, after which you can initialize your React Native DOM
scaffolding with the react-native dom

npm install --save-dev rnpm-plugin-dom
# or
yarn add --dev rnpm-plugin-dom

# Add DOM support to your React Native project
react-native dom

To run your initialized project in your browser, you can either:

  • Start the packager yourself using react-native start
    and navigate open your browser to localhost:8081/dom
  • Leverage the builtin rnpm command react-native run-dom
    which will start the packager and open the browser to the correct URL for you

Overview of files generated by the RNPM plugin

  • dom/bootstrap.js
    - Entrypoint to the main thread bundle where you can set runtime configuration options, register custom native modules, or any other JS initialization you would like to do.
  • dom/entry.js
    - Entrypoint to the JS thread bundle, will likely only be importing your App's entrypoint from the top-level folder of your project.
  • dom/index.html
    - HTML file which is what references and loads the JS bundles.
  • (conditionally) rn-cli.config.js
    - Depending on if the project already has one, the rnpm plugin will either create it with the proper configuration options to support the DOM platform or will simply add the necessary entries to your existing one.

Building for Production

A builtin script for performing a production build is still in the backlog but
here is a manual script which does so (assuming the same directory structure
that gets generated from the rnpm plugin).

# Ensure development-speecific code is stripped from the bundle
export NODE_ENV=production

# Build the main thread bundle
react-native bundle 
  --config $(pwd)/rn-cli.config.js 
  --dev false 
  --platform dom 
  --entry-file ./dom/bootstrap.js 
  --assets-dest ./dom/dist 
  --bundle-output ./dom/dist/bootstrap.bundle

# Build the JS thread bundle
react-native bundle 
  --config $(pwd)/rn-cli.config.js 
  --dev false 
  --entry-file ./dom/entry.js 
  --platform dom 
  --bundle-output ./dom/dist/entry.bundle 
  --assets-dest ./dom/dist

# Copy the index.html file to the build destination
cp dom/index.html dom/dist/index.html

The resulting folder in dom/dist
will contain static HTML & JS ready to be
deployed to your provider of choice.

Writting Native Modules/Views

Work In Progress

The API for this is going to be overhauled soon with accompanying documentation.
If you want to see what it currently looks like take a look at some of the built
in native modules such as AsyncLocalStorage

Repository Structure

This project is a lerna-managed monorepo with all the projects living in the packages

Package Overview

  • react-native-dom
    - The library itself (this is most likely the package you're interested in).
  • rnpm-plugin-dom
    - RNPM plugin primarily used for bootstrapping DOM support into a React Native project.
  • rndom-*
    - Custom web components (built with svelte
    ) used for some of the built-in widgets/views in react-native-dom

One noticeable omission to the list of packages is the custom build of Yoga
which can be found in this seperate repo
. yoga-dom
not included in this monorepo due to requiring a signifigantly different build
environment than this repo's entirely JS codebase.

Running RNTester/Examples

To run the examples located in the react-native-dom
source, run the following
commands from the root of the monorepo:

# be sure to update the git submodules to pull the RNTester code
git submodule update --init

# install dependencies
yarn && yarn compile

# start the react-native packager
yarn run-examples

Then navigate to localhost:8081/Examples
and choose which example you would
like to see.

A live deployment of the RNTester project (used primarily for manually testing
changes) can be found at




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