Pros of ChakraCore

• More mature and established project with a longer history
• Broader language support, including full ECMAScript 2015 (ES6) compatibility
• Better performance for complex JavaScript applications

Cons of ChakraCore

• Larger footprint and higher memory usage
• Slower startup time, especially for smaller applications
• Less optimized for mobile environments

Code Comparison

ChakraCore:

const engine = new ChakraCore.JsRuntime();
const context = engine.createContext();
const result = context.runScript('2 + 2');
console.log(result); // Output: 4

Hermes:

const hermes = require('hermes-engine');
const vm = new hermes.VM();
const result = vm.evaluate('2 + 2');
console.log(result); // Output: 4

Both engines provide similar functionality for running JavaScript code, but ChakraCore offers a more comprehensive API for advanced use cases. Hermes, on the other hand, focuses on simplicity and efficiency for mobile environments.

ChakraCore is better suited for complex web applications and desktop environments, while Hermes excels in mobile app development, particularly for React Native projects. The choice between the two depends on the specific requirements of your project, considering factors such as performance needs, target platform, and development ecosystem.

Pros of v8

• Widely adopted and battle-tested in major browsers like Chrome
• Extensive optimization techniques for high-performance JavaScript execution
• Supports a broader range of JavaScript features and ECMAScript standards

Cons of v8

• Larger memory footprint, which can be challenging for resource-constrained devices
• More complex codebase, potentially making it harder to customize for specific use cases
• Slower startup time compared to Hermes, especially on mobile devices

Code Comparison

v8 (C++):

Local<Context> context = Context::New(isolate);
Context::Scope context_scope(context);
Local<String> source = String::NewFromUtf8(isolate, "'Hello' + ', World!'");
Local<Script> script = Script::Compile(context, source).ToLocalChecked();
Local<Value> result = script->Run(context).ToLocalChecked();

Hermes (C++):

jsi::Runtime &runtime = hermes::makeHermesRuntime();
jsi::Value result = runtime.evaluateJavaScript(
    std::make_shared<jsi::StringBuffer>("'Hello' + ', World!'"),
    "inline");

Both v8 and Hermes are JavaScript engines, but they have different design goals and trade-offs. v8 focuses on high performance for general-purpose JavaScript execution, while Hermes is optimized for React Native mobile applications, prioritizing fast startup and lower memory usage.

Pros of Node.js

• Larger ecosystem with more packages and community support
• Broader application range, suitable for various server-side and desktop applications
• More mature and stable, with longer history and extensive production use

Cons of Node.js

• Larger runtime size, which can be less suitable for mobile or resource-constrained environments
• Generally slower startup time compared to Hermes
• Not optimized specifically for React Native applications

Code Comparison

Node.js:

const http = require('http');

const server = http.createServer((req, res) => {
  res.writeHead(200, { 'Content-Type': 'text/plain' });
  res.end('Hello World\n');
});

server.listen(3000);

Hermes:

// Hermes is primarily used in React Native, so a direct comparison is not applicable.
// However, here's a simple React Native component using Hermes:

import React from 'react';
import { Text, View } from 'react-native';

const HelloWorld = () => (
  <View>
    <Text>Hello World</Text>
  </View>
);

Note: Hermes is specifically designed as a JavaScript engine for React Native, while Node.js is a general-purpose JavaScript runtime. The code comparison showcases their different use cases rather than direct feature comparisons.

Pros of Deno

• Built-in TypeScript support without additional configuration
• Secure by default, with explicit permissions for file, network, and environment access
• Supports ES modules natively and has a built-in package manager

Cons of Deno

• Smaller ecosystem compared to Node.js, which Hermes is designed to work with
• Learning curve for developers familiar with Node.js
• Limited compatibility with existing Node.js packages

Code Comparison

Deno:

import { serve } from "https://deno.land/std@0.140.0/http/server.ts";

serve((req) => new Response("Hello, World!"));

Hermes (JavaScript runtime, typically used within React Native):

const http = require('http');

http.createServer((req, res) => {
  res.writeHead(200, {'Content-Type': 'text/plain'});
  res.end('Hello, World!');
}).listen(8080);

Summary

Deno and Hermes serve different purposes. Deno is a secure runtime for JavaScript and TypeScript, focusing on modern web standards. Hermes is a JavaScript engine optimized for React Native, prioritizing fast startup and low memory usage on mobile devices. While Deno offers built-in TypeScript support and security features, Hermes provides better performance for mobile applications within the React Native ecosystem.

Pros of JerryScript

• Extremely lightweight and suitable for resource-constrained devices
• Highly portable, supporting a wide range of platforms and architectures
• Compliant with ECMAScript 5.1 standard

Cons of JerryScript

• Limited support for modern JavaScript features
• Smaller community and ecosystem compared to Hermes
• Less optimized for mobile app performance

Code Comparison

JerryScript:

#include "jerryscript.h"

int main (void)
{
  const jerry_char_t script[] = "print('Hello, World!');";
  jerry_run_simple(script, sizeof(script) - 1, JERRY_INIT_EMPTY);
  return 0;
}

Hermes:

#include "hermes/hermes.h"

int main() {
  hermes::vm::RuntimeConfig conf;
  auto runtime = hermes::makeHermesRuntime(conf);
  runtime->runScript("print('Hello, World!');");
  return 0;
}

Both JerryScript and Hermes are JavaScript engines designed for embedded systems and mobile applications. JerryScript focuses on being ultra-lightweight and portable, making it ideal for IoT devices and resource-constrained environments. Hermes, developed by Facebook, is optimized for React Native mobile apps, offering better performance and smaller bundle sizes.

While JerryScript supports a broader range of platforms, Hermes provides better support for modern JavaScript features and is more tailored for mobile app development. The code examples demonstrate the simplicity of running JavaScript in both engines, with JerryScript using a C API and Hermes using a C++ API.

Pros of QuickJS

• Smaller footprint and faster startup time
• Easier to embed in other applications
• More compliant with ECMAScript standards

Cons of QuickJS

• Less optimized for mobile environments
• Smaller community and ecosystem
• Fewer performance optimizations for long-running applications

Code Comparison

QuickJS:

JSRuntime *rt = JS_NewRuntime();
JSContext *ctx = JS_NewContext(rt);
const char *code = "console.log('Hello, World!');";
JS_Eval(ctx, code, strlen(code), "<input>", JS_EVAL_TYPE_GLOBAL);
JS_FreeContext(ctx);
JS_FreeRuntime(rt);

Hermes:

jsi::Runtime *runtime = hermes::makeHermesRuntime();
jsi::Value result = runtime->evaluateJavaScript(
    std::make_unique<jsi::StringBuffer>("console.log('Hello, World!');"),
    "<input>");
delete runtime;

Key Differences

• QuickJS is written in C, while Hermes is primarily C++
• Hermes focuses on optimizing for React Native, while QuickJS aims for general-purpose use
• QuickJS provides a more complete JavaScript environment, including a built-in compiler
• Hermes emphasizes bytecode precompilation and optimized memory usage for mobile devices

Both engines serve different purposes, with QuickJS being more suitable for embedded systems and Hermes excelling in mobile app performance.