npmpackage.info

Gathering detailed insights and metrics for @margelo/hermes-profile-transformer

@margelo/hermes-profile-transformer - 0.0.10 | npmpackage.info

@margelo/hermes-profile-transformer

TypeScript tool for converting Hermes Sampling Profiler output to Chrome Dev Tools format

0.0.10

MIT

TypeScript

259.01 kB

2.9

Installations

npm install @margelo/hermes-profile-transformer

Developer Guide

BETA

Typescript

No

Module System

CommonJS

Min. Node Version

>=8

Node Version

20.12.2

NPM Version

10.9.0 Pull Requests

Open

16

Total

33

Closed

4

Merged

13

Issues

Open

7

Total

23

Closed

16

Releases

Unable to fetch releases

Languages

TypeScript

TypeScript (100%)

Developer

react-native-community

Download Statistics

Total Downloads

Last Day

Last Week

Last Month

Last Year

GitHub Statistics

MIT License

88 Stars

96 Commits

10 Forks

7 Watchers

15 Branches

69 Contributors

Updated on Apr 07, 2025

Maintainers

View All 69 Contributors

Package Meta Information

Latest Version

0.0.10

Package Id

@margelo/hermes-profile-transformer@0.0.10

Unpacked Size

259.01 kB

Size

62.54 kB

File Count

NPM Version

10.9.0

Node Version

20.12.2

Published on

Dec 18, 2024

Total Downloads

Cumulative downloads

Total Downloads

NaN

Last Day

NaN

Compared to previous day

Last Week

NaN

Compared to previous week

Last Month

NaN

Compared to previous month

Last Year

NaN

Compared to previous year

Weekly Downloads

Monthly Downloads

Yearly Downloads

Dependencies

source-map

Dev Dependencies

husky tsdx tslib typescript

Hermes Profile Transformer

Visualize Facebook's Hermes JavaScript runtime profile traces in Chrome Developer Tools.

Overview

The Hermes runtime, used by React Native for Android, is able to output Chrome Trace Events in JSON Object Format.

This TypeScript package converts Hermes CPU profiles to Chrome Developer Tools compatible JSON Array Format, and enriches it with line and column numbers and event categories from JavaScript source maps.

Usage

If you're using hermes-profile-transformer to debug React Native Android applications, you can use the React Native CLI react-native profile-hermes command, which uses this package to convert the downloaded Hermes profiles automatically.

As a standalone package

1const transformer = require('hermes-profile-transformer').default;
2const { writeFileSync } = require('fs');
3
4const hermesCpuProfilePath = './testprofile.cpuprofile';
5const sourceMapPath = './index.map';
6const sourceMapBundleFileName = 'index.bundle.js';
7
8transformer(
9  // profile path is required
10  hermesCpuProfilePath,
11  // source maps are optional
12  sourceMap,
13  sourceMapBundleFileName
14)
15  .then(events => {
16    // write converted trace to a file
17    return writeFileSync(
18      './chrome-supported.json',
19      JSON.stringify(events, null, 2),
20      'utf-8'
21    );
22  })
23  .catch(err => {
24    console.log(err);
25  });

Creating Hermes CPU Profiles

Opening converted profiles in Chrome Developer Tools

Open Developer Tools in Chrome, navigate to the Performance tab, and use the Load profile... feature.

API

transformer(profilePath: string, sourceMapPath?: string, bundleFileName?: string)

Parameters

Parameter	Type	Required	Description
profilePath	string	Yes	Path to a JSON-formatted `.cpuprofile` file created by the Hermes runtime
sourceMapPath	string	No	Path to a source-map compatible Source Map file
bundleFileName	string	No	If `sourceMapPath` is provided, you need to also provide the name of the JavaScript bundle file that the source map applies to. This file does not need to exist on disk.

Returns

Promise<DurationEvent[]>, where DurationEvent is as defined in EventInterfaces.ts.

Resources

Using Hermes with React Native.
Chrome Trace Event Format. Hermes uses the JSON Object format.
Measuring JavaScript performance in Chrome

LICENSE

MIT

No vulnerabilities found.

10

Dangerous-Workflow

Determines if the project's GitHub Action workflows avoid dangerous patterns.

10

Binary-Artifacts

Determines if the project has generated executable (binary) artifacts in the source repository.

10

License

Determines if the project has defined a license.

1

Code-Review

Determines if the project requires human code review before pull requests (aka merge requests) are merged.

0

Maintained

Determines if the project is "actively maintained".

0

Token-Permissions

Determines if the project's workflows follow the principle of least privilege.

0

Pinned-Dependencies

Determines if the project has declared and pinned the dependencies of its build process.

0

CII-Best-Practices

Determines if the project has an OpenSSF (formerly CII) Best Practices Badge.

0

Fuzzing

Determines if the project uses fuzzing.

0

Security-Policy

Determines if the project has published a security policy.

0

SAST

Determines if the project uses static code analysis.

0

Vulnerabilities

Determines if the project has open, known unfixed vulnerabilities.

Score

2.9

/10

Last Scanned on 2025-06-30

The Open Source Security Foundation is a cross-industry collaboration to improve the security of open source software (OSS). The Scorecard provides security health metrics for open source projects.

Learn More