title: How to unbind a function from an event among multiple functions?
body: <p>Say for example, we don't know how many functions already binded to an event. In that case we can bind our own function like below</p>
  
  <pre><code>var old = (element.onclick) ? element.onclick : function () {};
  element.onclick = function () {old(); myOwn()};
  </code></pre>
  
  <p>Now how to unbind myOwn function alone without disturbing others?</p>