Javascript Implementation of Levenshtein's Distance Algorithm

distance.js

/* (c) 2012, Stefan Schlesinger - http://sts.ono.at
 * 
 * My first version of a Javascript Levenshtein distance implementation.
 * http://en.wikipedia.org/wiki/Levenshtein_distance
 */

function unpack(str) {
    var bytes = [];
    for(var i = 0; i < str.length; i++) {
        var char = str.charCodeAt(i);
        bytes.push(char & 0xFF);
    }
    return bytes;
}

function distance(str1, str2) {
    var s = unpack(str1);
    var t = unpack(str2);
    var n = s.length;
    var m = t.length;
    if (n == 0) return m;
    if (m == 0) return n;
    
    # this array should be different
    var d = [0, 1, 2, 3];   
    var x;    
    for( var i=0; i<n; i++ ) {
        var e = i+1;
        for( var j=0; j<m; j++) {
            var cost = (s[i] == t[j]) ? 0 : 1;
            var x = Math.min(
                d[j+1] + 1, 
                e + 1,
                d[j] + cost
            );
            d[j] = e;
            e = x;
        }
        d[m] = x;
    }
    return x;
}


distance('hello', 'ehllo');