Merge duplicates in JSON array.

merge.js

/*
  merge.js
  Merge duplicates in JSON array.
*/

old_array = [
  {
    "Some": "data",
    "Here": "would",
    "Be": "nice",
    "Number": 123
  },
  {
    "Some": "data",
    "That": "has",
    "Duplicate": "keys",
    "Number": 456
  },
]

var new_obj = {}
for(sku in old_array) {
        // Create key (this is so you can test duplicates based on multiple keys in original array)
	key = old_array[sku].Key1 + " " + old_array[sku].Key2
	if(new_obj.hasOwnProperty(key)) {
                // If it already exists, merge data together
		// Now is an excellent time to log stuff
		new_obj[key].Quantity += parseInt(old_array[sku].Quantity)
    } else {
        // Create a new object
    	new_obj[key] = {
                // Duplicate object data
      }
    }
}

// Convert object to array
array = [];
for(sku in new_obj) {
    array.push(new_obj[sku])
}