jstime

Another JavaScript Runtime

Using the binary

You can find the latest jstime binary on the release page

Alternatively you can install with cargo

$ cargo install jstime

As a repl

$ jstime

Welcome to jstime!

>>

Run a script

$ cat hello-world.js
console.log("hello world");

$ jstime hello-world.js
hello world

Performance: JIT Warmup

For benchmarking or performance-critical scripts, use the --warmup flag to allow V8's JIT compiler to optimize the code:

$ jstime --warmup 10 benchmark.js

This runs the script 10 times before the actual execution, allowing TurboFan to profile and optimize hot code paths.

Embed it!

Check out the README.md for jstime-core for instructions on how to embed jstime in your rust application!

Features

jstime provides a minimal and performant JavaScript runtime with essential APIs.

For detailed documentation on all supported features, see Documentation.

👉 Check out the examples/ directory for runnable code samples!

Quick Overview

• Console API: console.log(), console.error(), etc.
• Timers: setTimeout(), setInterval(), and clearing functions
• Fetch API: Modern HTTP client with fetch(), Headers, Request, Response
• Streams API: ReadableStream, WritableStream, TransformStream for streaming data processing
• URL API: URL and URLSearchParams for URL manipulation
• Performance API: High-resolution timing with performance.now()
• Event API: Event and EventTarget for event handling
• Microtask API: queueMicrotask() for fine-grained async control
• Structured Clone API: structuredClone() for deep cloning of complex objects
• Base64 API: atob() and btoa() for base64 encoding/decoding
• Text Encoding API: TextEncoder and TextDecoder for UTF-8 encoding/decoding
• Crypto API: crypto.getRandomValues(), crypto.randomUUID(), crypto.subtle.digest() for cryptographic operations
• Process API: process.env, process.argv, process.cwd(), process.exit() for process information
• File System API: Complete Node.js-compatible fs/promises with readFile(), writeFile(), mkdir(), stat(), and more
• WebAssembly: Full WebAssembly support for running high-performance compiled modules
• ES Modules: Full support for import/export with top-level await, dynamic import(), and Node.js-compatible node_modules resolution
• Modern JavaScript: All ES2015+ features via V8 engine

Testing

jstime includes comprehensive test coverage including conformance tests for standard APIs:

• Console API - WHATWG Console Standard compliance
• Event API - WHATWG DOM Events compliance
• Timers API - WHATWG HTML Standard timers compliance
• Fetch API - WHATWG Fetch Standard compliance
• Streams API - WHATWG Streams Standard compliance
• URL API - WHATWG URL Standard compliance
• Performance API - W3C High Resolution Time compliance
• Structured Clone API - HTML Standard structured cloning compliance
• Base64 API - HTML Standard base64 encoding compliance
• Text Encoding API - WHATWG Encoding Standard compliance
• Crypto API - W3C Web Cryptography API compliance
• JSON Modules - ECMAScript JSON modules compliance
• WebAssembly - WebAssembly specification compliance

Run all tests with:

cargo test

For more details on conformance testing, see core/tests/CONFORMANCE_TESTS.md.