Sorting of Javascript array

Question

Say if I had a Javascript array as following and I sorted the array before printing it to console

var f = ["Salil", "Sam", "Anil", "John", "ajay", "Baba"];
f.sort();
console.log(f);

It prints as follows

Anil,Baba,John,Salil,Sameer,ajay

Why does ajay prints last, how does the case of the first letter plays a role?

thanks,

Salil

score 1 · Answer 1 · answered Sep 09 '13 at 18:33

The lower-case letters come after the upper-case letters in Unicode (in the base code page at least).

You can sort so that you pay no attention to case:

f.sort(function(w1, w2) {
  w1 = w1.toLowerCase(); w2 = w2.toLowerCase();
  return w1 < w2 ? -1 : w2 < w1 ? 1 : 0;
}

More complicated collations require more complicated comparison routines. The function you pass to .sort() should take two arguments, those being two members of the array to be compared. It's pretty important that your comparator function always returns the same answer for any two strings (in either order!), or else things can get weird.

score 1 · Answer 2 · answered Sep 09 '13 at 18:33

1

Because lowercase letters come after uppercase letters.

To enable caseless sorting, try this:

f.sort(function(a,b) {return a.toLowerCase() < b.toLowerCase() ? -1 : 1;});

answered Sep 09 '13 at 18:33

Niet the Dark Absol

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score 0 · Answer 3 · answered Sep 09 '13 at 18:43

Here is an example in long form to make it a bit clearer with the whole if/else if/else chain for returning -1/1/0 from the sort comparison:

var caseInsensitiveComparator = function(a, b) {
  var _a = a.toLowerCase(),
      _b = b.toLowerCase();

  if (_a < _b) {
    return -1;
  } else if (_b < _a) {
    return 1;
  } else {
    return 0;
  }
};

var f = ["Salil", "Sam", "Anil", "John", "ajay", "Baba"];
f.sort(caseInsensitiveComparator);
console.log(f);
> ["ajay", "Anil", "Baba", "John", "Salil", "Sam"]

The Mozilla Developer Network page on Array.prototype.sort has an explanation on how sort works.

Sorting of Javascript array

3 Answers3