How to sum the values of a JavaScript object?

Question

I\'d like to sum the values of an object.

I\'m used to python where it would just be:

sample = { \'a\': 1 , \'b\': 2 , \'c\':3 };
summed =  sum(sampl         


        

Answer 1

You could put it all in one function:

function sum( obj ) {
  var sum = 0;
  for( var el in obj ) {
    if( obj.hasOwnProperty( el ) ) {
      sum += parseFloat( obj[el] );
    }
  }
  return sum;
}
    
var sample = { a: 1 , b: 2 , c:3 };
var summed = sum( sample );
console.log( "sum: "+summed );

---

For fun's sake here is another implementation using Object.keys() and Array.reduce() (browser support should not be a big issue anymore):

function sum(obj) {
  return Object.keys(obj).reduce((sum,key)=>sum+parseFloat(obj[key]||0),0);
}
let sample = { a: 1 , b: 2 , c:3 };

console.log(`sum:${sum(sample)}`);

But this seems to be way slower: jsperf.com

Answer 2

A regular for loop is pretty concise:

var total = 0;

for (var property in object) {
    total += object[property];
}

You might have to add in object.hasOwnProperty if you modified the prototype.

Answer 3

Honestly, given our "modern times" I'd go with a functional programming approach whenever possible, like so:

const sumValues = (obj) => Object.keys(obj).reduce((acc, value) => acc + obj[value], 0);

Our accumulator acc, starting with a value of 0, is accumulating all looped values of our object. This has the added benefit of not depending on any internal or external variables; it's a constant function so it won't be accidentally overwritten... win for ES2015!

Answer 4

If you're using lodash you can do something like

_.sum(_.values({ 'a': 1 , 'b': 2 , 'c':3 })) 

Answer 5

A ramda one liner:

import {
 compose, 
 sum,
 values,
} from 'ramda'

export const sumValues = compose(sum, values);

Use: const summed = sumValues({ 'a': 1 , 'b': 2 , 'c':3 });

Answer 6

Use Lodash

 import _ from 'Lodash';
 
 var object_array = [{a: 1, b: 2, c: 3}, {a: 4, b: 5, c: 6}];
 
 return _.sumBy(object_array, 'c')
 
 // return => 9