How to compare Unicode strings in Javascript?

You have to keep two sortkey strings. One is for primary order, where German ä=a (primary a->a) and French é=e (primary sortkey e->e) and one for secondary order, where ä comes after a (translating a->azzzz in secondary key) or é comes after e (secondary key e->ezzzz). Especially in Czech some letters are variations of a letter (áéí…) whereas others stand in their full right in the list (ABCČD…GHChI…RŘSŠT…). Plus the problem to consider digraphs a single letters (primary ch->hzzzz). No trivial problem, and there should be a solution within JS.

Funny, I have to think about that problem and finished searching here, because it came in mind, that I can use my own javascript module. I wrote a module to generate a clean URL, therefor I have to translitate the input string... (http://pid.github.io/speakingurl/)

var mySlug = require('speakingurl').createSlug({
    maintainCase: true,
    separator: " "
});

var input = "Schöner Titel läßt grüßen!? Bel été !";
var result;

slug = mySlug(input);
console.log(result); // Output: "Schoener Titel laesst gruessen bel ete"

Now you can sort with this results. You can ex. store the original titel in the field "title" and the field for sorting in "title_sort" with the result of mySlug.