# Jsvu

> How to use jsvu for cross-engine testing.

- Skill: `v8/jsvu` (Agent Skill)
- Install (CLI): `npx skillmds@latest add v8/jsvu`
- Raw SKILL.md: https://api.skillmd.com/api/skills/v8/jsvu/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: v8 (https://skillmd.com/u/v8)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/v8/jsvu

---


# JSVU (JavaScript engine Version Updater)

Use `jsvu` to install and test across multiple JavaScript engines (e.g., v8,
spidermonkey, javascriptcore, chakra).

## Installation and Setup

For non-interactive installation and updating of specific engines on Linux, run:

```bash
npx jsvu --os=linux64 --engines=v8,spidermonkey,javascriptcore
```

You can customize the `--engines` flag with the engines you wish to test (e.g.,
`v8,v8-debug,spidermonkey,javascriptcore,graaljs`).

## Running Engines

Once installed, the engines are available in `~/.jsvu/bin/`. You can run them
directly:

```bash
~/.jsvu/bin/v8 my_test.js
~/.jsvu/bin/spidermonkey my_test.js
~/.jsvu/bin/javascriptcore my_test.js
```

This allows you to easily cross-reference behaviors and bugs against other major
JS engines.