How to sum value of two json object key?

Question

"bills": [
    {
        "refNo": 17,
        "billDate": "1-apr-2016",
        "dueDate": "30-apr-2016",
        "pendingAmount": 4500,
        "overdueDays": 28
    },
    {
        "refNo": 20,
        "billDate": "15-apr-2016",
        "dueDate": "3-may-2016",
        "pendingAmount": 56550,
        "overdueDays": 15
    }
]

I want to sum "pendingAmount" field. It should be return like pendingAmount: 61050

Answer 1

You can use Array#map and then Array#reduce to flatten your object and then sum the result of the map :

bills.map(bill => bill.pendingAmount).reduce((acc, amount) => acc + amount);

here's a snippet :

var bills = [
          {
            "refNo": 17,
            "billDate": "1-apr-2016",
            "dueDate": "30-apr-2016",
            "pendingAmount": 4500,
            "overdueDays": 28
          },
          {
            "refNo": 20,
            "billDate": "15-apr-2016",
            "dueDate": "3-may-2016",
            "pendingAmount": 56550,
            "overdueDays": 15
          }
        ];
var res = bills.map(bill => bill.pendingAmount).reduce((acc, amount) => acc + amount);
console.log(res)

Hope it helps,

Best regards,

Answer 2

The reduce() method applies a function against an accumulator and each element in the array (from left to right) to reduce it to a single value.

var bills = [
          {
            "refNo": 17,
            "billDate": "1-apr-2016",
            "dueDate": "30-apr-2016",
            "pendingAmount": 4500,
            "overdueDays": 28
          },
          {
            "refNo": 20,
            "billDate": "15-apr-2016",
            "dueDate": "3-may-2016",
            "pendingAmount": 56550,
            "overdueDays": 15
          }
        ];
        
        
      var result = bills.reduce(function(_this, val) {
          return _this + val.pendingAmount
      }, 0);

    console.log(result)
    //61050 answer