Javascript - array index issue in non sparse array
<p>non sparse array are contiguous in nature and from 0 to length-1, all index should return true for 'in' operator. It should be true also for empty element.</p>

<pre><code>obj1 = {x:1,y:2};
obj2 = Object.create(obj1);
obj2.z = 5;
var arr = [obj1,obj2,1,,2];

console.log(arr.length); //5
console.log(3 in arr);//false
</code></pre>

<p>index 3 is valid.
Why is it returning false?</p>

<p>Note: I am using latest firefox.</p>

<p>It should return false only for sparse array which doesn't have a specified index number 3.</p>

<p>Update: index 3 is valid so it should return true. in operator doesn't validate value of at the indexed position, it just validate the validity of index not the value</p>
