@react-native-community/cli-hermes

This package is part of the React Native CLI. It contains commands for managing the Hermes engine.

Installation

yarn add @react-native-community/cli-hermes

Commands

profile-hermes

Usage:

npx react-native profile-hermes [destinationDir] <flag>

Pull and convert a Hermes tracing profile to Chrome tracing profile, then store it in the directory of the local machine.

• destinationDir is optional, if provided, pull the file to that directory

  default: pull to the current React Native app root directory

Options

--filename <string>

File name of the profile to be downloaded, eg. sampling-profiler-trace8593107139682635366.cpuprofile.

default: pull the latest file

--raw

Pulls the original Hermes tracing profile without any transformation

--sourcemap-path <string>

The local path to your source map file if you generated it manually, ex. /tmp/sourcemap.json

--generate-sourcemap

Generate the JS bundle and source map in os.tmpdir()

--port <number>

The running metro server port number

default: 8081

--appId <string>

Specify an applicationId to launch after build. If not specified, package from AndroidManifest.xml will be used.

--appIdSuffix <string>

Specify an applicationIdSuffix to launch after build.

--host <string>

The host of the packager.

default: localhost

Notes on source map

This step is recommended in order for the source map to be generated:

If you are planning on building a debug APK, that will run without the packager, by invoking ./gradlew assembleDebug you can simply set bundleInDebug: true in your app/build.gradle file, inside the project.ext.react map.