Sum the same object of array

Question

var data = [ {id:1, qty:100}, {id:2, qty:200}, {id:1, qty:100}, {id:2, qty:200} ];

How to sum this array become to [ {id:1, qty:200}, {id:2, qty:

Answer 1

I didn't get to run this on any data, but the logic seems right. Basically this code goes through your array, and for each unique instance it will store the values into a temporary array and the write over the original array with the results.

var temp = [];
temp.push(data[0])
for (x = 1; x < data.length; x++){
  for (i = 0; i < temp.length; i++){
    if (temp[i].id != data[x].id && temp[i].qty != data[x].qty ){
      temp.push[data[x]];
    }
  }
}
data = temp;