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Run JavaScript code from Python

Project description


Run JavaScript code from Python.

PyExecJS is a porting of ExecJS from Ruby. PyExecJS automatically picks the best runtime available to evaluate your JavaScript program, then returns the result to you as a Python object.

A short example:

>>> import execjs
>>> execjs.eval("'red yellow blue'.split(' ')")
['red', 'yellow', 'blue']
>>> ctx = execjs.compile("""
...     function add(x, y) {
...         return x + y;
...     }
... """)
>>>"add", 1, 2)

Of course, you can pick particular JavaScript runtime by get() function:

>>> default = execjs.get() # the automatically picked runtime
>>> default.eval("1 + 2")
>>> jscript = execjs.get("JScript")
>>> jscript.eval("1 + 2")
>>> node = execjs.get("Node")
>>> node.eval("1 + 2")

If EXECJS_RUNTIME environment variable is specified, PyExecJS pick the JavaScript runtime as a default:

>>> #execjs.get().name # this value is depends on your environment.
>>> os.environ["EXECJS_RUNTIME"] = "Node"
>>> execjs.get().name
'Node.js (V8)'

PyExecJS supports these runtimes:


$ pip install PyExecJS


$ easy_install PyExecJS


Copyright (c) 2012 Omoto Kenji. Copyright (c) 2011 Sam Stephenson and Josh Peek.

Released under the MIT license. See LICENSE for details.



  • Supported Python 3.3
  • Fixed file handle leaking
  • Fixed issue with passenger-nginx-4.0


  • Removed “import execjs” (it prevent execution of by Python 2.6)


  • Javascript sources were embeded in ‘which’ command were reimplemented by pure python.


  • Python 2.6.x was supported.


  • Forgotten shell=True was added to Popen.


  • First release.

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