How to iterate over objects in array and sum a property without iterating? [duplicate]

Question

Is it possible to add up all duration values of an object array without iteration?

const data = [
  {
    duration: 10
    any: 'other fields'
  },
  {
    duration: 20
    any: 'other fields'
  }
]

Result should be '30'.

let result = 0
data.forEach(d => {
  result = result + d.duration
})
console.log(result)

no, it is not possible to iterate an array without iteration - by the way, I recommend using reduce ... let result = data.reduce((r, d) => r + d.duration, 0); — Jaromanda X
– Jaromanda X, Commented Jul 29, 2017 at 8:03
It's not possible. An efficient way to do this would be to use reduce developer.mozilla.org/en/docs/Web/JavaScript/Reference/… — Fawaz
– Fawaz, Commented Jul 29, 2017 at 8:05
I believe quantum computers are capable of solving this problem without iterating. — user663031
– user663031, Commented Jul 29, 2017 at 11:34
While it is an unfeasible notion to attempt to iterate without using iteration, one may use recursion instead of iteration to extract the indicated object property value from each of the array's objects and total those values. In fact, "...iteration is just a special case of recursion (tail recursion)" (see: ocf.berkeley.edu/~shidi/cs61a/wiki/Iteration_vs._recursion). See example code at codepen.io/anon/pen/YxwdpR — slevy1
– slevy1, Commented Jul 30, 2017 at 23:29

Nina Scholz · Accepted Answer · 2017-07-29 08:06:18Z

4

I does not work without some iteration, to get a sum of a specified property.

You could use Array#reduce with a callback and a start value of zero.

const data = [{ duration: 10, any: 'other fields' }, { duration: 20, any: 'other fields' }];
let result = data.reduce((r, d) => r + d.duration, 0);

console.log(result);

answered Jul 29, 2017 at 8:06

Nina Scholz

388k26 gold badges367 silver badges417 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Hassan Imam · Accepted Answer · 2017-07-29 08:11:52Z

3

You can't accomplish this without iteration. You can use array#reduce , which uses iteration.

const data = [
  {
    duration: 10,
    any: 'other fields'
  },
  {
    duration: 20,
    any: 'other fields'
  }
];

var result = data.reduce(
  (sum, obj) => sum + obj['duration'] 
  ,0
);

console.log(result)

.as-console-wrapper { max-height: 100% !important; top: 0; }

answered Jul 29, 2017 at 8:11

Hassan Imam

22.6k6 gold badges45 silver badges53 bronze badges

Collectives™ on Stack Overflow

How to iterate over objects in array and sum a property without iterating? [duplicate]

2 Answers 2

Comments

Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Linked

Related