Compare 2 file names by grouping digits and non-digits.

compareFileNames.js

function compareFileNames(a, b) {
  if (a && b) {
    var aParts = (a + '').match(/\d+|\D+/g) || [],
        bParts = (b + '').match(/\d+|\D+/g) || [];
    if (/\d/.test(aParts[0]) == /\d/.test(bParts[0])) {
      for (var x, i = 0, l = Math.min(aParts.length, bParts.length); i < l; i++) {
        if (aParts[i] != bParts[i]) {
          return (/\d/.test(aParts[i]) && (x = parseInt(aParts[i], 10) - parseInt(bParts[i], 10)))
            ? x
            : aParts[i] < bParts[i] ? -1 : 1;
        }
      }
    }
    return a < b ? a == b ? 0 : -1 : 1;
  }
  return a ? 1 : -1;
}