Get the sum of matching object in vue js

Question

I have an array with few objects. I want to create a new array with sum of matching object.

var array = [
        {bill_no:123,paid:30 },
        {bill_no:123,paid:30 },
        {bill_no:345,paid:12 },
        {bill_no:345,paid:12 },
        {bill_no:444,paid:10 },
        {bill_no:555,paid:12 },
      ]

I want the ouput like

 {bill_no:123,paid:60},{bill_no:345,paid:24},{bill_no:555,paid:12}

Can we please get little bit more information on the part "New array with sum of matching object". Does this mean you want to add bill1 and bill2 and return the paid price? — Luay, Jul 19 '18 at 13:33
Possible duplicate of [How to merge duplicates in an array of objects and sum a specific property?](https://stackoverflow.com/questions/38294781/how-to-merge-duplicates-in-an-array-of-objects-and-sum-a-specific-property) — yuriy636, Jul 19 '18 at 13:41

BlackBeard · Accepted Answer · 2018-07-19T13:55:28.717

IMHO, you can use array#reduce and array#findIndex to do something like this:

var arr = [
        {bill_no:123,paid:30 },
        {bill_no:123,paid:30 },
        {bill_no:345,paid:12 },
        {bill_no:345,paid:12 },
        {bill_no:444,paid:10 },
        {bill_no:555,paid:12 },
      ]

var sum = arr.reduce((a, obj) => {
  let i = a.findIndex(o => o.bill_no == obj.bill_no);
  i == (-1) ? a.push(obj) : (a[i].paid += obj.paid);
  return a;
}, []);

console.log(sum);

score 1 · Answer 2 · answered Jul 19 '18 at 13:45

You can use Array.reduce() with find() operation inside the reduce():

var array = [
    {bill_no:123,paid:30 },
    {bill_no:123,paid:30 },
    {bill_no:345,paid:12 },
    {bill_no:345,paid:12 },
    {bill_no:444,paid:10 },
    {bill_no:555,paid:12 },
];
var res = array.reduce((acc, obj)=>{
  var existObj = acc.find(item => item.bill_no === obj.bill_no);
  if(existObj){
    existObj.paid += obj.paid;
    return acc;
  }
  acc.push(obj);
  return acc;
}, []);
console.log(res);

Get the sum of matching object in vue js

2 Answers2