call an external javascript function from python

Question

I have a javascript function that I can call with input and that returns a result. I can integrate this javascript function into an html-document (of course).

Now I would like to call exactly this javascript function from python. I have a python programm and want to call the javascript function with input parameters passed to the JS function by the calling python function. And the JS function shall return some result to python.

This JS function has quite complex functionality and is used in a web project also. I would like to use same functionality in Python.

Does anyone know how to solve this? Python is quite huge so I think I only did not find the required python module up until know. I spent 2 days in searching a possibility.

Thanks!

• user2665694: This question does not make much sense since Python is likely running somewhere on your server and Javascript is executed within the browser. Or?
• Marcel Korpel: Perhaps it helps if you tell us what it is exactly that you want to achieve.
• Frode: Why the downvote? It's a legitimate question.
• mikerobi: @Frode, probably because it's not a very useful question. Asking "How do I eat an apple when I only have a banana?" is also a valid question.
• Frode: @mikerobi, Walter has a library written in Javascript that he wants to utilize in his Python script. I just don't see how asking for ways to do this not useful and relevant on stackoverflow, but fair enough. +1 from me.

Answer 1

pyv8 will let you use the V8 JS engine from Python.

If the JavaScript function depends on things that are not core JavaScript (such as DOM) then you will need to find implementations of those.

• mikerobi: I think the added complexity probably exceeds the effort to rewrite the function, especially if the OP is using windows, where V8 is notoriously difficult to compile.
• Quentin: If it is ported, then you have to maintain two versions of it.
• Walter: That is esactly the reason. I don't want to maintain two versions of the same function. That will result in problems sooner or later.

Answer 2

I had similar requirement recently and solved via node.

parser.js

module.exports = {decode}; // entry for node
function decode(payload) {
 var decoded = {};
 // ...
 console.log(JSON.stringify(decoded));
 return decoded;
}

terminal

node -e 'require("./parser.js").decode("foobar")'

output: the parsed data

caller.py

import subprocess
cmd = """node -e 'require(\"./parser.js\").decode(\"{}\")'"""
output = subprocess.check_output(cmd.format(data), shell=True)