Adding library function for sorting array gives undefined

Question

I am trying to add a Library function for sorting Items in an array. Though I got link and way, but when trying to make a library function, this doesn't work. can someone help me out as it is responding undefined as result.

var arr1 = [5, 4, 2, 6, 9, 2, 8, 1, 6];

Array.prototype.sortItems = function(){
  this.sort((a,b) => a - b);
}

console.log(arr1.sortItems());

Reference:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort

The solution is in the link you've added: "Return value: The sorted array. Note that the array is sorted in place, and no copy is made." — Andreas
– Andreas, Commented Jun 6, 2020 at 9:47
How do you want log a result without return from your function? — Ala Eddine Menai
– Ala Eddine Menai, Commented Jun 6, 2020 at 9:55

Yousaf · Accepted Answer · 2020-06-06 09:40:10Z

2

you need to return the result of this.sort()

var arr1 = [5, 4, 2, 6, 9, 2, 8, 1, 6];

Array.prototype.sortItems = function(){
  return this.sort((a,b) => a - b);
}

console.log(arr1.sortItems());

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

answered Jun 6, 2020 at 9:40

Yousaf

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User863 · Accepted Answer · 2020-06-06 09:41:01Z

1

Try returning the result

var arr1 = [5, 4, 2, 6, 9, 2, 8, 1, 6];

Array.prototype.sortItems = function(){
  return this.sort((a,b) => a - b);
}

console.log(arr1.sortItems());

FYI, compareFunction is optional

var arr1 = [5, 4, 2, 6, 9, 2, 8, 1, 6];

console.log(arr1.sort());

answered Jun 6, 2020 at 9:41

User863

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1 Comment

Deadpool Over a year ago

yes 'compare function' is optional, but without it data like [5,4,2,1,100,57...] won't work! So, for proper working, its required!

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