title: fabric.js assign event listener to an object for multiple events
body: <p>I am asking this mainly out of curiosity as it is possible to replicate code but being deep in rails at the minute, repetition makes me feel dirty and I can't find it in the docs.</p>
  
  <p>Suppose I have a <code>rect = fabric.Rect</code> and I wanted to add a listener for say, moving and modified that do the same thing:</p>
  
  <pre><code>rect.on('moving', function() {
      console.log('moving or modified'); 
  });
  
  rect.on('modified', function() {
      console.log('moving or modified'); 
  });
  </code></pre>
  
  <p>is it possible to combine these in some way?</p>
  
  <p>I'm very new to JS and so this could be a simple thing in JS that I've not come across yet but again, it's not mentioned in Fabric docs that I've seen.</p>