title: Underscore.js: Replace item in collection
body: <p>I've been using underscore.js for a week now and I really like it.
  However, now I want to replace a single element in collection (vm.lists) with another element.
  I tried doing the following:</p>
  
  <pre><code>_.each(vm.lists, function (el) {
      if (el.id == list.id)
          el = list;
  });
  </code></pre>
  
  <p>and:</p>
  
  <pre><code>var l = _.findWhere(vm.lists, { id: list.id });
  l = list;
  </code></pre>
  
  <p>But none of them changes the actual item in the collection. How would I do this properly?</p>