Sorting functions for JavaScript

String.prototype.isBefore = function(string) {
    if(string.indexOf(' ') != -1) throw "Error : Not supported character [space]";
    string = string.toLowerCase();
    string = string.replace(/[àâáãäå]+/gim, 'a');
    string = string.replace(/[èêéë]+/gim, 'e');
    string = string.replace(/[ìîíï]+/gim, 'i');
    string = string.replace(/[òôóöõø]+/gim, 'o');
    string = string.replace(/[ùûúü]+/gim, 'u');
    string = string.replace(/[ýÿ]+/gim, 'y');
    string = string.replace(/[ñ]+/gim, 'n');

    var alpha = 'abcdefghijklmnopqrstuvwxyz';
    var first = this.toString();
    var second = string.toString();
    var minLength = (first.length > second.length) ? second.length : first.length;
    var bool = false;
    var equal = true;

    for(var i=0; i<minLength && bool==false; i++) {
        if(alpha.indexOf(first[i]) < alpha.indexOf(second[i])) {
            bool = true;
            equal = false;
        }
        else if(alpha.indexOf(first[i]) > alpha.indexOf(second[i]))
            equal = false;

        if(alpha.indexOf(first[i]) == -1) throw "Error : Not supported character '"+ first +"' on index "+ i;
        if(alpha.indexOf(second[i]) == -1) throw "Error : Not supported character '"+ second +"' on index "+ i;
    }

    if(equal) bool = true;

    return bool;
};
String.prototype.isAfter = function(string) {
    if(string.indexOf(' ') != -1) throw "Error : Not supported character [space]";
    string = string.toLowerCase();
    string = string.replace(/[àâáãäå]+/gim, 'a');
    string = string.replace(/[èêéë]+/gim, 'e');
    string = string.replace(/[ìîíï]+/gim, 'i');
    string = string.replace(/[òôóöõø]+/gim, 'o');
    string = string.replace(/[ùûúü]+/gim, 'u');
    string = string.replace(/[ýÿ]+/gim, 'y');
    string = string.replace(/[ñ]+/gim, 'n');

    var alpha = 'abcdefghijklmnopqrstuvwxyz';
    var first = string.toString();
    var second = this.toString();
    var minLength = (first.length > second.length) ? second.length : first.length;
    var bool = false;
    var equal = true;

    for(var i=0; i<minLength && bool==false; i++) {
        if(alpha.indexOf(first[i]) < alpha.indexOf(second[i])) {
            bool = true;
            equal = false;
        }
        else if(alpha.indexOf(first[i]) > alpha.indexOf(second[i]))
            equal = false;

        if(alpha.indexOf(first[i]) == -1) throw "Error : Not supported character '"+ first +"' on index "+ i;
        if(alpha.indexOf(second[i]) == -1) throw "Error : Not supported character '"+ second +"' on index "+ i;
    }

    if(equal) bool = true;

    return bool;
};