JAVASCRIPT

call python function from javascript

All you need is to make an ajax request to your pythoncode. You can do this with jquery http://api.jquery.com/jQuery.ajax/, or use just javascript

$.ajax({
  type: "POST",
  url: "~/pythoncode.py",
  data: { param: text}
}).done(function( o ) {
   // do something
});

call javascript function from python

You need to install js2py or requests-html packages to run the JavaScript program from Python

//example :
//javaScript function : squareofNum()
code in python : 
import js2py

squareofNum = "function f(x) {return x*x;}"

result = js2py.eval_js(squareofNum)

print(result(5))
>>output : 25