How to $.extend 2 objects by adding numerical values together from keys with the same name?
<p>I currently have 2 obj and using the jquery extend function, however it's overriding value from keys with the same name. How can I add the values together instead?</p>

<pre><code>var obj1 = {
  "orange": 2,
  "apple": 1,
  "grape": 1
};

var obj2 = {
  "orange": 5,
  "apple": 1,
  "banana": 1
};

mergedObj = $.extend({}, obj1, obj2);

var printObj = typeof JSON != "undefined" ? JSON.stringify : function (obj) {
  var arr = [];

  $.each(obj, function (key, val) {
    var next = key + ": ";
    next += $.isPlainObject(val) ? printObj(val) : val;
    arr.push(next);
  });

  return "{ " + arr.join(", ") + " }";
};

console.log('all together: ' + printObj(mergedObj));
</code></pre>

<p>And I get <code>obj1 = {"orange":5,"apple":1, "grape":1, "banana":1}</code></p>

<p>What I need is  <code>obj1 = {"orange":7,"apple":2, "grape":1, "banana":1}</code></p>
