Getting the return value of Javascript code in Selenium

You can return values even if you don't have your snippet of code written as a function like in the below example code, by just adding return var; at the end where var is the variable you want to return.

result = driver.execute_script('''
cells = document.querySelectorAll('a');
URLs = [];
[].forEach.call(cells, function (el) {
    URLs.push(el.href)
});
return URLs
''')

result will contain the array that is in URLs this case.

To return a value, simply use the return JavaScript keyword in the string passed to the execute_script() method, e.g.

>>> from selenium import webdriver
>>> wd = webdriver.Firefox()
>>> wd.get("http://localhost/foo/bar")
>>> wd.execute_script("return 5")
5
>>> wd.execute_script("return true")
True
>>> wd.execute_script("return {foo: 'bar'}")
{u'foo': u'bar'}
>>> wd.execute_script("return foobar()")
u'eli'