react-native-chunks

A tool that allows you to split your bundle into several smaller chunks. This is very helpful for OTA bundles when some shared parts of your bundle remain unchanged (such as localizations, third-party libraries, or internationalization polyfills). It can significantly reduce your OTA bundle size. For example, see the codepush-example, where the zipped CodePush bundle is reduced by up to 400 KB (only React Native and changed files are included in the bundle).

Installation

Step 1: Install the package

yarn add react-native-chunks

Step 2: Add metro config

Wrap your metro.config into withChunksConfig helper

const { withChunksConfig } = require('react-native-chunks/metro-config')

const config = getConfig(getDefaultConfig(__dirname), {
  // ...
})

module.exports = withChunksConfig(config)

Step 3: Create chunks config file

Create chunks.config.json file in the root of the project. You can check description of file config structure here.

{
  "outputDir": "./.chunks",
  "chunks": [{
    "name": "core",
    "entryFile": "src/core/index.ts",
    "exclude": [
      "node_modules/react-native"
    ]
  }]
}

Step 4: Add chunk-bundle command

Android

1. set bundleCommand as chunk-bundle command in the android/app/build.gradle

/* Bundling */
//   A list containing the node command and its flags. Default is just 'node'.
// nodeExecutableAndArgs = ["node"]
//
//   The command to run when bundling. By default is 'bundle'
-// bundleCommand = "ram-bundle"
+bundleCommand = "chunk-bundle"
//
//   The path to the CLI configuration file. Default is empty.
// bundleConfig = file(../rn-cli.config.js)

2. add CHUNKS_APK_BUILD_TIME to defaultConfig in the android/app/build.gradle

android {
    ndkVersion rootProject.ext.ndkVersion
    buildToolsVersion rootProject.ext.buildToolsVersion
    compileSdk rootProject.ext.compileSdkVersion

    namespace "chunks.example"
    defaultConfig {
        applicationId "chunks.example"
+       resValue 'string', "CHUNKS_APK_BUILD_TIME", String.format("\"%d\"", System.currentTimeMillis())
        minSdkVersion rootProject.ext.minSdkVersion
        targetSdkVersion rootProject.ext.targetSdkVersion
        versionCode 1
        versionName "1.0"
    }

iOS

In .xcode.env add CLI_PATH and BUNDLE_COMMAND

# This `.xcode.env` file is versioned and is used to source the environment
# used when running script phases inside Xcode.
# To customize your local environment, you can create an `.xcode.env.local`
# file that is not versioned.

+export CLI_PATH="../node_modules/react-native/cli.js"
+export BUNDLE_COMMAND="chunk-bundle"

# NODE_BINARY variable contains the PATH to the node executable.
#
# Customize the NODE_BINARY variable here.
# For example, to use nvm with brew, add the following line
# . "$(brew --prefix nvm)/nvm.sh" --no-use
export NODE_BINARY=$(command -v node)

Commands

chunks

chunks builds chunks and places the output in the outputDir specified in the chunks.config.json file.

react-native chunks --platform android

1. You can buld only one chunk with --chunk

react-native chunks --platform android --chunk core

2. Usually, if the hash of the dependent files has not changed, the chunks command does not rebuild chunks. You can add the --force flag to force it to rebuild the chunks.

react-native chunks --platform android --force

chunk-bundle

The chunk command builds chunks and the main bundle. It functions similarly to react-native bundle, but it builds the chunks before the main bundle.

react-native chunk-bundle --platform android

chunks-compose-sourcemaps

The chunks-compose-sourcemaps command composes all sourcemaps into one. This command collects all sourcemaps from the chunks and composes them with the provided --bundle-sourcemap. The output is the composed source map, which is written to the file specified in --bundle-sourcemap-output. If --bundle-sourcemap-output is not defined, the output will be written to --bundle-sourcemap.

yarn react-native chunks-compose-sourcemaps --platform android --bundle-sourcemap ./android/app/build/generated/sourcemaps/react/release/index.android.bundle.map

Configuration

react-native-chunks has a configuration mechanism that allows changing its behavior and providing additional features. react-native-chunks can be configured by creating a chunks.config.js at the root of the project.

interface ChunksConfig {
  /**
   * The output directory where the bundled chunks should be located.
   **/
  outputDir?: string

  chunks?: Array<{
    /**
     * Name of the chunk
     **/
    name: string
    /**
     * The entry point of the chunk.
     **/
    entryFile: string
    
    /**
     * Path to files that should be excluded from chunks.
     * This can be helpful when a chunk uses shared libraries that are already present in the main bundle, such as react-native.
     *
     * Example:
     * 
     * exclude: ['**/node_modules/react-native/**', '<rootDir>/src/index.js', { deps: true, pattern: '**/node_modules/react/**' }]
     **/
    exclude?: Array<string | { deps?: boolean; pattern: string }>

    /**
     * Path to files that should be included in the chunk.
     * This can be helpful when a chunk should include some modules, even if they are excluded by the exclude option.
     *
     * Example:
     * 
     * exclude: ['**/node_modules/react-native/**', '<rootDir>/src/index.js', { deps: true, pattern: '**/node_modules/react/**' }]
     **/
    include?: Array<string | { deps?: boolean; pattern: string }>

    /**
     * [Optional]
     * 
     * The output directory where the bundled chunk should be located. This overrides the root outputDir property.
     **/
    outputDir?: string
  }>

  bundle?: {
/**
     * Path to files that should be excluded from the bundle.
     *
     * Example:
     * 
     * exclude: ['**/node_modules/react-native/**', '<rootDir>/src/index.js', { deps: true, pattern: '**/node_modules/react/**' }]
     **/
    exclude?: Array<string | { deps?: boolean; pattern: string }>

    /**
     * Path to files that should be included in the bundle.
     *
     * Example:
     * 
     * exclude: ['**/node_modules/react-native/**', '<rootDir>/src/index.js', { deps: true, pattern: '**/node_modules/react/**' }]
     **/
    include?: Array<string | { deps?: boolean; pattern: string }>
  }
}

Sourcemaps

react-native-chunks builds small chunks, resulting in several bundles and sourcemap files. To see the correct stack trace in monitoring systems like Sentry and Bugsnag, you need to compose the sourcemap file before sending it to these monitoring systems.

You can do it via chunks-compose-sourcemaps command. Please check the description for more details.

Debugging & Developer Mode

It works only for production builds, so debugging and developer mode are not affected in any way.

Under the hood

See "Under the hood section for more details.

Contributing

See the contributing guide to learn how to contribute to the repository and the development workflow.

License

MIT

Made with create-react-native-library