Executing Javascript from Python

Question

I have HTML webpages that I am crawling using xpath. The etree.tostring of a certain node gives me this string:

<script>
<!--
function escramble_758(){
  var a,b,c
  a='+1 '
  b='84-'
  a+='425-'
  b+='7450'
  c='9'
  document.write(a+c+b)
}
escramble_758()
//-->
</script>

I just need the output of escramble_758(). I can write a regex to figure out the whole thing, but I want my code to remain tidy. What is the best alternative?

I am zipping through the following libraries, but I didnt see an exact solution. Most of them are trying to emulate browser, making things snail slow.

• http://code.google.com/p/python-spidermonkey/ (clearly says it's not yet possible to call a function defined in Javascript)
• http://code.google.com/p/webscraping/ (don't see anything for Javascript, I may be wrong)
• http://pypi.python.org/pypi/selenium (Emulating browser)

Edit: An example will be great.. (barebones will do)

Answer 1

You can also use Js2Py which is written in pure python and is able to both execute and translate javascript to python. Supports virtually whole JavaScript even labels, getters, setters and other rarely used features.

import js2py

js = """
function escramble_758(){
var a,b,c
a='+1 '
b='84-'
a+='425-'
b+='7450'
c='9'
document.write(a+c+b)
}
escramble_758()
""".replace("document.write", "return ")

result = js2py.eval_js(js)  # executing JavaScript and converting the result to python string 

Advantages of Js2Py include portability and extremely easy integration with python (since basically JavaScript is being translated to python).

To install:

pip install js2py