title: JS: How can I prevent access to the global variables do?
body: <p>Is to disable the global variable in the function that I want.</p>
  
  <p>I would make like Expenssion of <code>Adobe After Effect</code></p>
  
  <p>example code :</p>
  
  <pre><code>function privateFunction(){
      return window;
  }
  </code></pre>
  
  <p>then normally :</p>
  
  <pre><code>result : Window Object
  </code></pre>
  
  <p>but I want then :</p>
  
  <pre><code>result : undefined
  </code></pre>
  
  <p>What should I do?</p>
  
  <p>please help me</p>
  
  <p>I want blocking global variable access in function;</p>