I have two arrays, old and new, which hold objects at each position. How would I sync or find the delta (i.e. what is new, updated and deleted from the new array compared to the old array)

var o = [
    {id:1, title:"title 1", type:"foo"},
    {id:2, title:"title 2", type:"foo"},
    {id:3, title:"title 3", type:"foo"}
];

var n = [
    {id:1, title:"title 1", type:"foo"},
    {id:2, title:"title updated", type:"foo"},
    {id:4, title:"title 4", type:"foo"}
];

With the above data, using id as the key, we'd find that item with id=2 has an updated title, item with id=3 is deleted, and item with id=4 is new.

Is there an existing library out there that has useful functions, or is it a case of loop and inner loop, compare each row..e.g.

for(var i=0, l=o.length; i<l; i++)
{   
    for(var x=0, ln=n.length; x<ln; x++)
    {
        //compare when o[i].id == n[x].id    
    }  
}

Do this kind of comparison three times, to find new, updated and deleted?

javascript synchronization
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