JavaScript sum all of the values in each object in an array?

You could map the objects and the values by iterating the keys of ths object and add the value of all properties.

Methods used:

• Array#map for returning a result for every item

• Object.keys for getting all own properties of an object

• Array#reduce for summing up the values

var data = [{ a: 1, b: 2, c: 3, d: 4 }, { a: 2, b: 3, c: 4, d: 5 }],
    sum = data.map(function (object) {
        return Object.keys(object).reduce(function (sum, key) {
            return sum + object[key];
        }, 0);
    });

console.log(sum);

Sum without key 'a'

var data = [{ a: 1, b: 2, c: 3, d: 4 }, { a: 2, b: 3, c: 4, d: 5 }],
    sum = data.map(function (object) {
        return Object.keys(object).reduce(function (sum, key) {
            return sum + (key !== 'a' && object[key]);
        }, 0);
    });

console.log(sum);

Short solution using Array.prototype.reduce() function:

var sum = [{a:1, b:2, c:3, d:4},{a:2, b:3, c:4, d:5}],
    result = sum.reduce(function (r, o) {
        r.push(Object.keys(o).reduce(function(r, b){ return r + o[b]; }, 0));
        return r;
    }, []);

console.log(result);

In the following code, o is each object in the array, t is the accumulating total sum, p is the property of the object being added.

const sum = [{a:1, b:2, c:3, d:4},{a:2, b:3, c:4, d:5}];

const result = sum.map(o => Object.keys(o).reduce((t, p) => t + o[p], 0));

console.log(result);

es6 for of version:

let sum = [{a:1, b:2, c:3, d:4},{a:2, b:3, c:4, d:5}];

let result = [], objSum;
for (let item of sum) {
    objSum = 0;
    for (let property in item) {
        if (item.hasOwnProperty(property)) {
            objSum += item[property];
        }
    }

    result.push(objSum);
}
console.log(result);//[10, 14]

You may do as follows in pure JS in 2017.

var sum = [{a:1, b:2, c:3, d:4},{a:2, b:3, c:4, d:5}],
   sums = sum.map(a => Object.values(a).reduce((p,c) => p+c));
console.log(sums);

Or you can use a utility library like Lodash.

var _ = require('lodash');

var sum = [{a:1, b:2, c:3, d:4},{a:2, b:3, c:4, d:5}];
var result = _.map(sum, function(obj) {
      return _.reduce(_.values(obj), function(sum, n) {
          return sum + n;
      }, 0);
});
console.log(result);