title: Copy a 'change' EventListener function
body: <p>I have this HTML tag</p>
  
  <pre><code>&lt;input type="file" id="File"&gt;
  </code></pre>
  
  <p>which has an event listener </p>
  
  <pre><code>document.getElementById("File").addEventListener("change", function() {alert("test")});
  </code></pre>
  
  <p>I would like to copy the function in the listener but all the following lines return null or undefined</p>
  
  <pre><code>document.getElementById("File").getAttribute("change")
  //null
  document.getElementById("File").change
  //undefined
  document.getElementById("File").getAttribute("onchange")
  //null
  document.getElementById("File").onchange
  //null
  </code></pre>
  
  <p>How can I copy the anonymous function from the listener?</p>