get the first and second highest values of an array using javascript

Question

I am trying to perform the following code:

function oldestAges(ages){
    if (ages == []){
      return [0,0]; 
    }else{
      var max = Math.max.apply(null, ages); 
              ages.splice(ages.indexOf(max), 1); 
      var max2 = Math.max.apply(null, ages); 
      return [max2,max];
  }
}

However, when testing [] as ages, the expected was '[0, 0]', instead got: '[-Infinity, -Infinity]'

Also, is there a much easier way to accomplish the same task? I ask because using R I could get the same result in much less number of lines. I am noob in javascript still.

You can't use == to compare arrays by their contents. The operator compares only by object identity, so one array will never ever be == to another array. — Pointy
– Pointy, Commented Oct 1, 2018 at 20:32
The simple way is to sort the array and then return the first two elements. — Barmar
– Barmar, Commented Oct 1, 2018 at 20:33
As @Barmar implied: the problem is in this line: if (ages == []){ - it will always return false — Nir Alfasi
– Nir Alfasi, Commented Oct 1, 2018 at 20:50

Jeto · Accepted Answer · 2018-10-01 20:37:18Z

4

A simple (not sure about the most optimal) way to achieve this:

const input = [5, 150, 2, 8, 58, 4];

const result = input.sort((x, y) => y - x).slice(0, 2);

console.log(result);

answered Oct 1, 2018 at 20:37

Jeto

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Comments

user10243107 · Accepted Answer · 2018-10-01 20:37:15Z

1

You can sort your array in descending order so that the first two elements contain the highest values.

ages.sort((a, b) => b - a);

Now ages[0] and ages[1] contain the two biggest numbers.

answered Oct 1, 2018 at 20:37

user10243107

Comments

Fatih Aktaş · Accepted Answer · 2018-10-01 20:40:49Z

1

ages.length == 0 is what you can use to see if the number of the elements in the array is zero.

Your code has an error where you say if (ages == []).

Try this,

function oldestAges(ages){
        if (ages.length == 0){
          return [0,0];
        }else{
          var max = Math.max.apply(null, ages);
                  ages.splice(ages.indexOf(max), 1);
          var max2 = Math.max.apply(null, ages);
          return [max2,max];
      }
    }

answered Oct 1, 2018 at 20:40

Fatih Aktaş

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