title: Find model in Backbone.js collection by cid rather than id
body: <p>Can I use Collection.get(id) to find a model within a Backbone.js collection by cid, for a model not yet saved to the server?   </p>
  
  <p>From the documentation, it seems like .get should find a model by either its id or cid.   However, <code>collection.get(cid)</code> doesn't find the model, whereas this does, <code>collection.find(function(model) {return model.cid===cid; })</code>.  Presumably I'm overlooking something basic.</p>
  
  <p><a href="http://jsfiddle.net/gradualstudent/ReTQk/4/" rel="nofollow noreferrer">jsFiddle for example below</a></p>
  
  <pre><code>var Element = Backbone.Model.extend({});
  var Elements = Backbone.Collection.extend({ model:  Element });
  
  var elements = new Elements(), el, cids = [];
  
  for (var i=0; i&lt;4; i++) {
      el = new Element({name: "element"+i})
      elements.add(el);
      cids.push(el.cid);
  }
  
  console.log(cids);
  el1 = elements.get(cids[0]);     
  console.log(el1);  // undefined
  
  
  el1a = elements.find(function(model) { return model.cid === cids[0]; });
  console.log(el1a);  // success
  </code></pre>
  
  <p><a href="https://stackoverflow.com/questions/12169822/backbone-js-id-vs-idattribute-vs-cid">Backbone.js - id vs idAttribute vs cid</a></p>