title: Query on Execution environment of JavaScript & Python
body: <p>Below diagram is retrieved after running JavaScript code(top-half) on <a href="http://jstutor.herokuapp.com/" rel="nofollow noreferrer">link1</a> and python code(bottom-half) on <a href="http://pythontutor.com/" rel="nofollow noreferrer">link2</a></p>
  
  <p><img src="https://i.stack.imgur.com/q4OgK.png" alt="enter image description here"></p>
  
  <p>My question:</p>
  
  <p>I see that names <code>foo</code> &amp; <code>bar</code> are already sitting in global frame(in blue) of JavaScript Execution environment(EE) unlike python's EE? How did JavaScript interpreter know about these two names before starting interpretation?</p>