DukPy

0.5.1 · active · verified Wed Apr 15

DukPy is a simple, lightweight JavaScript interpreter for Python, embedding the Duktape JavaScript engine. It allows executing JavaScript code directly from Python applications. As of version 0.5.1, it supports modern Python versions (up to 3.14) and maintains a steady release cadence, often aligning with new Python releases or Duktape engine updates.

Warnings

breaking Support for older Python versions (2.x, 3.4-3.6) has been deprecated and eventually removed. Modern versions of DukPy require Python 3.7+.
Fix: Upgrade Python to version 3.7 or newer. If legacy Python is unavoidable, use an older DukPy version (not recommended).
gotcha Versions prior to 0.4.0 might crash or produce incorrect output when handling JavaScript strings containing unicode emoji or other non-Basic Multilingual Plane (BMP) characters, due to encoding issues.
Fix: Upgrade to DukPy 0.4.0 or newer, which switched to CESU-8 encoding for better Unicode handling.
gotcha Versions prior to 0.2.2 contained a memory leak in the `dukpy.evaljs` function, which could lead to increased memory consumption in long-running applications.
Fix: Upgrade to DukPy 0.2.2 or newer to benefit from the memory leak fix.
gotcha When using `python_functions` to expose Python callables to JavaScript, ensure the function name matches exactly. Older versions (pre-0.3.1) might provide less informative error messages if the function is not found.
Fix: Upgrade to DukPy 0.3.1 or newer for improved error messages, and always double-check function names when setting up Python callbacks.
gotcha If pre-built wheels are not available for your specific platform/Python version, `pip install dukpy` will attempt to build from source, which requires a C compiler (e.g., GCC or Clang) installed on your system.
Fix: Ensure a C compiler is installed, or use an environment where pre-built wheels are provided (e.g., common Linux distros, macOS, Windows with official Python releases).

Install

pip install dukpy Install DukPy

Imports

evaljs
```
import dukpy; dukpy.evaljs(...)
```

Quickstart

Demonstrates basic JavaScript evaluation, passing data from Python to JavaScript, and calling Python functions from within JavaScript.

import dukpy

# Basic JavaScript evaluation
result = dukpy.evaljs("1 + 2")
print(f"1 + 2 = {result}")

# Passing data to JavaScript
result = dukpy.evaljs("a + b", data={'a': 10, 'b': 20})
print(f"a + b (with data) = {result}")

# Calling Python functions from JavaScript
def my_python_sum(x, y):
    return x + y

js_code = "var sum = my_python_sum(5, 7); sum;"
result = dukpy.evaljs(js_code, python_functions={'my_python_sum': my_python_sum})
print(f"JS calling Python function = {result}")

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