quickjs-emscripten (install size 7.5mb) - mostly backwards compatible all-in-one package. This package installs the WASM files for DEBUG_SYNC, DEBUG_ASYNC, RELEASE_SYNC and RELEASE_ASYNC variants as NPM dependencies. Its total install size is reduced from ~
quickjs-emscripten-core (install size 573kb) - just the Typescript code, should be compatible with almost any runtime. You can use this with a single a-la-carte build variant, such as @jitl/quickjs-wasmfile-release-sync to reduce the total install size needed to run QuickJS to ~1.1mb.
Several a-la-carte build variants, named @jitl/quickjs-{wasmfile,singlefile-{esm,cjs,browser}}-{debug,release}-{sync,asyncify}. See the [quickjs-emscripten-core docs][core-docs] for more details.

ESModules & Browser support

quickjs-emscripten uses [package.json export conditions][conditions] to provide native ES Modules for NodeJS and the browser when appropriate. Most bundlers, like Webpack@5 and Vite, will understand conditions and work out of the box. This should enable advanced tree-shaking, although I'm not sure how much benefit is possible with the library.

You can also use quickjs-emscripten directly from an HTML file in two ways:

<!doctype html>
<!-- Import from a ES Module CDN -->
<script type="module">
  import { getQuickJS } from "https://esm.run/quickjs-emscripten@0.25.0"
  const QuickJS = await getQuickJS()
  console.log(QuickJS.evalCode("1+1"))
</script>

In edge cases, you might want to use the IIFE build which provides QuickJS as the global QJS.

<!doctype html>
<!-- Add a script tag to load the library as the QJS global -->
<script
  src="https://cdn.jsdelivr.net/npm/quickjs-emscripten@0.25.0-rc.11/dist/index.global.js"
  type="text/javascript"
></script>
<!-- Then use the QJS global in a script tag -->
<script type="text/javascript">
  QJS.getQuickJS().then((QuickJS) => {
    console.log(QuickJS.evalCode("1+1"))
  })
</script>

Breaking Changes

We now differentiate between runtime environments at build time using Node.JS package.json [export conditions in subpath exports][conditions], instead of including support for all environments in a single build. While this resolves open issues with relatively modern bundlers like webpack@5 and vite, it may cause regressions if you use an older bundler that doesn't understand the "browser" condition.
The release variants - RELEASE_SYNC (the default), and RELEASE_ASYNC - no longer embed the WebAssembly code inside a JS file. Instead, they attempt to load the WebAssembly code from a separate file. Very old bundlers may not understand this syntax, or your web server may not serve the .wasm files correctly. Please test in a staging environment to verify your production build works as expected.
quickjs-emscripten now uses [subpath exports in package.json][conditions]. Imports of specific files must be removed. The only valid import paths for quickjs-emscripten are:
- import * from 'quickjs-emscripten' (the library)
- import packageJson from 'quickjs-emscripten/package.json'
- import { DEBUG_SYNC, DEBUG_ASYNC, RELEASE_SYNC, RELEASE_ASYNC } from 'quickjs-emscripten/variants' (these are exported from the main import, but are also available as their own files)
You should update your imports to use one of these paths. Notably, the WASM files can no longer be directly imported from the quickjs-emscripten package.
If you have errors about missing type files, you may need to upgrade to typescript@5 and set moduleResolution to node16 in your tsconfig.json. This shouldn't be necessary for most users.