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jsvu is theJavaScript (engine)VersionUpdater.

jsvu makes it easy to install recent versions of various JavaScript engines without having to compile them from source.

Note:jsvu requires Node.js v18+. (jsvu follows the latestactive LTS version of Node.)

Install thejsvu CLI:

npm install jsvu -g

Modify your dotfiles (e.g.~/.bashrc) to add~/.jsvu/bin to yourPATH:

export PATH="${HOME}/.jsvu/bin:${PATH}"

Then, runjsvu:

jsvu

On first run,jsvu prompts you for your operating system and architecture, and the list of JavaScript engines you wish to manage throughjsvu. It then downloads and installs the latest version of each of the engines you selected.

To update the installed JavaScript engines later on, just runjsvu again.

^* JavaScriptCore requires external dependencies to run on Windows:

• On 32-bit Windows, installiTunes.
• On 64-bit Windows, download the latestWebKitRequirements and add itsbin64 directory to yourPATH.

eshost-cli makes it easy to run and compare code in all JavaScript engines thatjsvu installs.

First, installeshost-cli:

npm install -g eshost-cli

Then, either automatically configurejsvu-installed hosts:

eshost --configure-jsvu

…or telleshost-cli wherejsvu installs each JavaScript engine following the instructions below.

eshost --add'GraalJS' graaljs~/.jsvu/bin/graaljseshost --add'JavaScriptCore' jsc~/.jsvu/bin/javascriptcoreeshost --add'QuickJS' qjs~/.jsvu/bin/quickjseshost --add'SpiderMonkey' jsshell~/.jsvu/bin/spidermonkeyeshost --add'V8 --harmony' d8~/.jsvu/bin/v8 --args'--harmony'eshost --add'V8' d8~/.jsvu/bin/v8eshost --add'XS' xs~/.jsvu/bin/xs

eshost --add"GraalJS" graaljs"%USERPROFILE%\.jsvu\bin\graaljs.cmd"eshost --add"JavaScriptCore" jsc"%USERPROFILE%\.jsvu\bin\javascriptcore.cmd"eshost --add"SpiderMonkey" jsshell"%USERPROFILE%\.jsvu\bin\spidermonkey.cmd"eshost --add"V8 --harmony" d8"%USERPROFILE%\.jsvu\bin\v8.cmd" --args"--harmony"eshost --add"V8" d8"%USERPROFILE%\.jsvu\bin\v8.cmd"eshost --add"XS" xs"%USERPROFILE%\.jsvu\bin\xs.cmd"

That’s it! You can now run code snippets in all those engines with a single command:

eshost -e'new RegExp("\n").toString()'# https://crbug.com/v8/1982eshost -e'(function maxCallStackSize() { try { return 1 + maxCallStackSize(); } catch (_) { return 1; }}())'eshost -e'Date.parse("1 Octopus 2018")'

On your personal devices, the only command you’ll ever need isjsvu as described above. There are no command-line flags to remember. 👋🏻

However, there are use cases for running jsvu within non-interactive environments (e.g. as part of continuous integration), where it’s desirable to bypass the initialjsvu prompt asking to confirm your operating system, architecture, and the list of JavaScript engines to install. Here’s how to do that:

jsvu --os=linux64 --engines=all# Equivalent to:jsvu --os=linux64 --engines=graaljs,hermes,javascriptcore,quickjs,spidermonkey,v8,xs

If the operating system and architecture are not known in advance, the--os=default flag attempts to guess the correct value from the running environment. This might not be right for example if running a 32-bit Node.js process on a 64-bit machine.

Note that--engines=all does not install thev8-debug binaries.

jsvu also supports installing specific versions alongside the main engine binaries (which it keeps up to date). Here’s an example:

jsvu v8@7.2.502

Binaries installed using this method are named${BINARY}-${VERSION}, so that the above example installs a binary namedv8-7.2.502. This way, there’s never any conflict with the mainv8 binary, which jsvu can keep up to date.

This feature works for all the supported engines:

jsvu graaljs@20.2.0jsvu hermes@0.6.0jsvu javascriptcore@242640jsvu quickjs@2019-08-18jsvu spidermonkey@66.0b13jsvu v8@7.2.502jsvu v8-debug@7.1.302jsvu xs@8.7.0

If you pass in an invalid version number, or if the JavaScript engine creators don’t provide a precompiled binary for that specific version, jsvu shows an error.

As a shorthand, forv8 andv8-debug builds, jsvu can even figure out the last known good revision within amilestone. To install the latest available V8 v7.2.x for example, run:

jsvu v8@7.2# jsvu figures out that this means v7.2.502, and then installs that version.

jsvu avoids the need forsudo privileges by installing everything in~/.jsvu/bin rather than, say,/usr/bin.

jsvu downloads files over HTTPS, and only uses URLs that are controlled by the creators of the JavaScript engine or, in the case of JavaScriptCore on Linux, the port maintainers.

1. On themain branch, bump the version number inpackage.json:

   npm version patch -m'Release v%s'

   Instead ofpatch, useminor ormajoras needed.

   Note that this produces a Git commit + tag.

2. Push the release commit and tag:

   git push&& git push --tags

   Our CI then automatically publishes the new release to npm.

Mathias Bynens (@mathias)