title: Compare 2 arrays of objects with Underscore to find the differnce
body: <p>I have 2 arrays, one is newVal and the other is origVal define</p>
  
  <p>orig:</p>
  
  <pre><code>[
  {"ListingId":1762276,"Rating":3,"ListPrice":7411828,"PropertyType":"Residential"},
  {"ListingId":1826692,"Rating":3,"ListPrice":650000,"PropertyType":"Residential"},
  {"ListingId":1833283,"Rating":4,"ListPrice":950000,"PropertyType":"Residential"},
  {"ListingId":1832134,"Rating":3,"ListPrice":850000,"PropertyType":"Residential"},
  {"ListingId":1829932,"Rating":4,"ListPrice":750000,"PropertyType":"Residential"},
  {"ListingId":1827548,"Rating":5,"ListPrice":650000,"PropertyType":"Residential"}
  ]
  </code></pre>
  
  <p>new:</p>
  
  <pre><code>[
  {"ListingId":1762276,"Rating":2,"ListPrice":7411828,"PropertyType":"Residential"},
  {"ListingId":1826692,"Rating":3,"ListPrice":650000,"PropertyType":"Residential"},
  {"ListingId":1833283,"Rating":4,"ListPrice":950000,"PropertyType":"Residential"},
  {"ListingId":1832134,"Rating":3,"ListPrice":850000,"PropertyType":"Residential"},
  {"ListingId":1829932,"Rating":4,"ListPrice":750000,"PropertyType":"Residential"},
  {"ListingId":1827548,"Rating":5,"ListPrice":650000,"PropertyType":"Residential"}
  ]
  </code></pre>
  
  <p>If I change one of the ratings in new, how might I detect that change, and retrieve the changed object? </p>
  
  <p>There will only be one change at a time, although I don't think that matters.</p>
  
  <p>FYI: These arrays are being produced from an Anjularjs  watchcollection</p>
  
  <pre><code>$scope.$watchCollection('items', function (new, old) {
  
  }, true); 
  </code></pre>
  
  <p>Thank you,
  Stephen </p>