quickjs-cffi

Python binding for QuickJS Javascript Engine using cffi. Supports x86_64 and aarch64 platforms.

NOTE: Currently supported operating system is Linux (manylinux_2_28 and musllinux_1_2)

Install

pip install quickjs-cffi

Features

• ✅ Use npm to install packages and use them directly
• ✅ In case you need to use complex ECMAScript or TypeScript modules/libraries/packages see Yjs example below how to use esbuild to transpile their code to QuickJS compatible ECMAScript modules
• ✅ Import remote and local ECMAScript scripts/modules
• ✅ Define Python objects and pass them to JavaScript
• ✅ Define JavaScript objects and pass them to Python
• ✅ Python objects live in Python environment
• ✅ JavaScript objects live in JavaScript environment
• ✅ Freely use Python objects in JavaScript
• ✅ Freely use JavaScript objects in Python

Usage

from quickjs import JSEval, JSRuntime, JSContext, JSError

# create runtime and context
rt = JSRuntime()
ctx: JSContext = rt.new_context()

# load lodash from remote location
# it also accepts local JavaScript files
ctx.load('https://raw.githubusercontent.com/lodash/lodash/refs/heads/main/dist/lodash.min.js')
lodash: JSValue = ctx['_']

# call lodash.range to create array JavaScript side
# and return its handler to Python side
r: JSValue = lodash.range(10, 100, 10)

# on Python side, define JavaScript function
# and use it to filter JavaScript array
f0: JSValue = ctx.eval('n => n >= 50')
r: JSValue = lodash.filter(lodash.range(10, 100, 10), f0)

# on Python side, define Python function
# and use on JavaScript side to filter array
def f1(n, *args):
    return n >= 50

r: JSValue = lodash.filter(lodash.range(10, 100, 10), f1)

# on Python side, define Python lambda function
# and use on JavaScript side to filter array
f2 = lambda n, *args: n >= 50 # noqa
r: JSValue = lodash.filter(lodash.range(10, 100, 10), f2)

# on Python side, define pass inplace Python lambda function
# and use on JavaScript side to filter array
r: JSValue = lodash.filter(lodash.range(10, 100, 10), lambda n, *args: n >= 50)

# on Python side, define Python lambda function
# then set it as global function in JavaScript
# and use it on JavaScript side to filter array
ctx['f3'] = lambda n, *args: n >= 50
r: JSValue = lodash.filter(lodash.range(10, 100, 10), ctx.eval('f3'))

Build

python -m venv venv
source venv/bin/activate
pip install poetry
poetry install --all-extras

Demos

First setup temp node project, so node modules can be installed and used inside QuickJS examples:

npm init -y
npm install esbuild

Huge number of isoloted JavaScript contexts:

python -B examples/demo_contexts.py

Lodash example:

npm install lodash
python -B examples/demo_lodash.py

Handlebas example:

npm install handlebars
python -B examples/demo_handlebars.py

Yjs example:

npm install yjs
esbuild node_modules/yjs/src/index.js --bundle --outfile=examples/yjs.js --format=iife --loader:.ts=ts --global-name="Y"
python -B examples/demo_yjs.py