Sort Danish alphabetically using JavaScript?

Question

Is there a library or cross-browser native implementation to sort an array of Danish strings alphabetically in JavaScript?

[Aalborg, Sorø ...]

Answer 1

Unfortunately @Tibos solution doesnt work. The danish letters æøå is not sortable as a dane would expect. And it certainly wont work with aa, which is considered as an oldschool å. The only solution is to make an "handheld" sort-algorithm.

Here is working solution :

arr.sort(function(a,b) {
    function getCode(c) {
        c=c.toLowerCase();
        if (c.substring(0,2)=='aa') return 300; 
        switch (c.charCodeAt(0)) {
            case 229 : //å
                return 299;
                break;
            case 248 : //ø
                return 298;
                break;
            case 230 : //æ
                return 297;
                break;
            default : 
                return c.charCodeAt(0);
                break;
        }
    }
    return getCode(a) - getCode(b);
});

The test array

var arr = ['Ølby', 'Ålestrup', 'Ærø', 'Almindingen', 'Aalborg', 'Sorø'];

is by locale sorted as

["Ølby", "Ærø", "Ålestrup", "Sorø", "Almindingen", "Aalborg"]

Which is totally wrong. The above function sort the array correct :

["Almindingen", "Sorø", "Ærø", "Ølby", "Ålestrup", "Aalborg"]

---

Update

@tibos was absolutely right. The above algorithm just sort by the first letter. The below function converts the strings to array of integers, according to the sorting-scheme from the algorithm above. Then it compares the integer arrays - by that, the strings are sorted in their full length :

arr.sort(function(a,b) {
    var d, e, f;
    function getIntArray(c) {
        var array=[];
        c=c.toLowerCase();
        for (var i=0;i<c.length;i++) {
            if (c.substring(i,2)=='aa') {
                array.push(300); 
                i++;
            } else {
                switch (c.charCodeAt(i)) {
                    case 229 : //å
                        array.push(299);
                        break;
                    case 248 : //ø
                        array.push(298);
                        break;
                    case 230 : //æ
                        array.push(297);
                        break;
                    default : 
                        array.push(c.charCodeAt(i));
                        break;
                }
            }
        }
        return array;
    }
    d=getIntArray(a);
    e=getIntArray(b);
    for (f=0;f<d.length;f++) {
        if (d[f]!=e[f]) {
            return d[f] - e[f];
        }
    }
});

test array :

var arr = ['Ølby', 'Ålborg', 'Århus', 'Ålestrup', 'Åkikrkeby', 'Ærø', 'Almindingen', 'Aalborg', 'Sorø'];

is now sorted in full length :

["Almindingen", "Sorø", "Ærø", "Ølby", "Åkikrkeby", "Ålborg", "Ålestrup", "Århus", "Aalborg"]