title: Modify a JavaScript variable with Selenium
body: <p>I have a boolean JavaScript variable named <code>foo</code> that I would like to change the value of from true to false. The variable has global scope.</p>
  
  <p>In Selenium, how can I change the value of this variable?</p>
  
  <p>(The variable, hidden to the user, disables a CPU-intensive feature that causes Selenium to choke.)</p>