JS: Find largest number in array of objects

Question

What's the easiest way to find the largest number in an array of objects and return that object?

var arr = [ { num: 0.5 }, { num: 1 }, { num: 0.35 }]

Tried to use forEach but couldn't work out a way to do this, other than storing every number and comparing them.

Any help is appreciated. Thanks in advance.

You don't store every number, you just loop through exactly once and keep a reference to whichever one is the current largest. Although you do need to think about what to do if more than one element has the same high number. — nnnnnn
– nnnnnn, Commented Feb 29, 2016 at 0:51

RobG · Accepted Answer · 2016-02-29 00:57:45Z

15

reduce will do the job:

var maxObj = arr.reduce(function(max, obj) {
  return obj.num > max.num? obj : max;
});

answered Feb 29, 2016 at 0:57

RobG

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1 Comment

realph Over a year ago

Reduce is what I was looking for.Thanks for this. Really elegant way to achieve the solution to my problem,

Sarantis Tofas · Accepted Answer · 2016-02-29 01:00:00Z

2

returns the object with the largest number:

var arr = [ { num: 0.5 }, { num: 1 }, { num: 0.35 }]
var res = Math.max.apply(Math,arr.map(function(o){return o.num;}))
var obj = arr.find(function(o){ return o.num == res; })
console.log(obj);

answered Feb 29, 2016 at 1:00

Sarantis Tofas

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Comments

Michail Michailidis · Accepted Answer · 2016-02-29 01:05:33Z

0

You could use lodash?

   var arr = [ { num: 0.5 }, { num: 1 }, { num: 0.35 }]
   var max = _.max(arr, function(item) {
      return item.num;
   });

per aquinas suggestion - switched _.sortBy with _.max (there is no _.maxBy anymore) plunkr: https://plnkr.co/edit/TYIou2GUUxRWcXoCXHnv?p=preview

edited Feb 29, 2016 at 1:05

answered Feb 29, 2016 at 0:52

Michail Michailidis

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2 Comments

aquinas Over a year ago

Ack. Don't sort to find the largest number. If you are going to use lodash at all use maxby. _.maxBy(arr,"num")

Michail Michailidis Over a year ago

@aquinas good point O(NlogN) is worse than O(N) - btw there is no _.maxBy anymore.. _.max is doing what is needed

guest271314 · Accepted Answer · 2016-02-29 05:14:30Z

0

Try using Math.max(), JSON.stringify() , String.prototype.match()

var arr = [ { num: 0.5 }, { num: 1 }, { num: 0.35 }];
var res = arr[(m = Math.max.apply(Math, n = JSON.stringify(arr).match(/(\d+\.\d+)|(\d+)/g))) && n.indexOf(m+"")];

edited Feb 29, 2016 at 5:14

answered Feb 29, 2016 at 1:03

guest271314

1

12 Comments

nnnnnn Over a year ago

But that doesn't return an object. OP wants to get the object with the Max value, not just the value.

guest271314 Over a year ago

@nnnnnn "But that doesn't return an object." ? Yes, it does; see bracket notation at res = arr[/* Math.max() */]

nnnnnn Over a year ago

Maybe I'm just being particularly dense today, but aren't you trying to use the maximum .num property as an index into the original array? That won't work.

RobG Over a year ago

The "bit in brackets" returns the max value, that is then used as an index to the original array. It "works" because in the OP, the max value is 1 and the related object is at index 1. Make the max value say 3 at index 0 and see what happens.

RobG Over a year ago

Well, I guess you beat it into submission eventually. ;-) Not sure JSON.stringify is a sensible approach, and in /(\d+.\d+)|(\d+)/g the period should be quoted.

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