hermes-engine

What is hermes-engine?

The hermes-engine npm package provides a JavaScript engine optimized for running React Native applications. It is designed to improve performance and reduce memory usage, making it ideal for mobile applications.

What are hermes-engine's main functionalities?

Running JavaScript Code

Hermes-engine allows you to run JavaScript code snippets and get the results. This is useful for executing scripts within a controlled environment.

const { Hermes } = require('hermes-engine');
const hermes = new Hermes();
const result = hermes.evaluate('1 + 1');
console.log(result); // Outputs: 2

Bytecode Compilation

Hermes-engine can compile JavaScript code to bytecode, which can then be executed more efficiently. This is particularly useful for performance-critical applications.

const { compileToBytecode } = require('hermes-engine');
const bytecode = compileToBytecode('function add(a, b) { return a + b; }');
console.log(bytecode);

Memory Management

Hermes-engine provides manual control over garbage collection, allowing developers to manage memory usage more effectively.

const { Hermes } = require('hermes-engine');
const hermes = new Hermes();
hermes.gc();
console.log('Garbage collection completed');

Other packages similar to hermes-engine

v8

The v8 package provides bindings to the V8 JavaScript engine, which is used in Google Chrome and Node.js. It offers high performance and is widely used in server-side applications. Compared to hermes-engine, V8 is more general-purpose and not specifically optimized for React Native.

quickjs

QuickJS is a small and embeddable JavaScript engine. It is designed to be lightweight and fast, making it suitable for embedded systems. While it shares some performance goals with hermes-engine, it is not specifically tailored for React Native applications.

duktape

Duktape is an embeddable JavaScript engine with a focus on portability and compactness. It is suitable for embedded systems and IoT devices. Unlike hermes-engine, Duktape is not optimized for mobile applications and React Native.

README

Hermes

Hermes is a small and lightweight JavaScript VM optimized for running React Native apps on Android.

See hermesengine.dev for more information.

This package contains a Hermes bytecode compiler for Windows, Linux and macOS, plus Android runtime libraries.

Additional tools are available in hermes-engine-cli.