Sort Array Elements (string with numbers), natural sort

Question

I have an array like;

["IL0 Foo", "PI0 Bar", "IL10 Baz", "IL3 Bob says hello"] 

And need to sort it so it appears like;

["IL0 Foo", "IL3 Bob says hello", "IL10 Baz", "PI0 Bar"] 

I have tried a sort function;

function compare(a,b) {   if (a < b)      return -1;   if (a > b)     return 1;   return 0; } 

but this gives the order

["IL0 Foo", "IL10 Baz", "IL3 Bob says hello", "PI0 Bar"] 

I have tried to think of a regex that will work but can't get my head around it.
If it helps the format will always be 2 letters, x amount of numbers, then any number of characters.

Answer 1

This is called "natural sort" and can be implemented in JS like this:

function naturalCompare(a, b) {      var ax = [], bx = [];        a.replace(/(\d+)|(\D+)/g, function(_, $1, $2) { ax.push([$1 || Infinity, $2 || ""]) });      b.replace(/(\d+)|(\D+)/g, function(_, $1, $2) { bx.push([$1 || Infinity, $2 || ""]) });            while(ax.length && bx.length) {          var an = ax.shift();          var bn = bx.shift();          var nn = (an[0] - bn[0]) || an[1].localeCompare(bn[1]);          if(nn) return nn;      }        return ax.length - bx.length;  }    /////////////////////////    test = [      "img12.png",      "img10.png",      "img2.png",      "img1.png",      "img101.png",      "img101a.png",      "abc10.jpg",      "abc10",      "abc2.jpg",      "20.jpg",      "20",      "abc",      "abc2",      ""  ];    test.sort(naturalCompare)  document.write("<pre>" + JSON.stringify(test,0,3));

To sort in reverse order, just swap the arguments:

test.sort(function(a, b) { return naturalCompare(b, a) }) 

or simply

test = test.sort(naturalCompare).reverse();