Variable: default

February 16, 2026 · View on GitHub

const default: QuickJSAsyncVariant

Docs | Variant with separate .WASM file. Supports browser ESM, NodeJS ESM, and NodeJS CommonJS.

Variable	Setting	Description
library	quickjs	The original bellard/quickjs library. Version 2025-09-13+f1139494 vendored to quickjs-emscripten on 2026-02-15.
releaseMode	debug	Enables assertions and memory sanitizers. Try to run your tests against debug variants, in addition to your preferred production variant, to catch more bugs.
syncMode	asyncify	Build run through the ASYNCIFY WebAssembly transform. This imposes substantial size (2x the size of sync) and speed penalties (40% the speed of sync). In return, allows synchronous calls from the QuickJS WASM runtime to async functions on the host. The extra magic makes this variant slower than sync variants. Note that both variants support regular async functions. Only adopt ASYNCIFY if you need to! The QuickJSAsyncRuntime and QuickJSAsyncContext classes expose the ASYNCIFY-specific APIs.
emscriptenInclusion	wasm	Has a separate .wasm file. May offer better caching in your browser, and reduces the size of your JS bundle. If you have issues, try a 'singlefile' variant.
exports	require import browser workerd	Has these package.json export conditions