SO - 29364262

by Arun P Johny

JavaScript

var array = [{
    Id: "001",
    qty: 1
}, {
    Id: "002",
    qty: 2
}, {
    Id: "001",
    qty: 2
}, {
    Id: "003",
    qty: 4
}];

var result = [];
array.reduce(function (res, value) {
    if (!res[value.Id]) {
        res[value.Id] = {
            qty: 0,
            Id: value.Id
        };
        result.push(res[value.Id])
    }
    res[value.Id].qty += value.qty
    return res;
}, {});

console.log(result)