gistfile1.txt

String.prototype.generateSubstrings = function() {
    var string = this;
    var stringLen = string.length;
    var innerIterWtf = function(substrings, i, j) {
        if (j == stringLen)
            return substrings
        else {
            var substring = string.slice(i, j+1);
            substrings.push(substring);
            return innerIterWtf(substrings, i, j+1);
        }
    };
    var iter = function(substrings, i) {
        if (i == stringLen-1)
            return substrings;
        else {
            innerIterWtf(substrings, i, i+1);
            return iter(substrings, i+1);
        }
    };
    return iter([], 0);
}

String.prototype.isPalindrome = function() {
    return this == this.split('').reverse().join('');;
}

Array.prototype.sortByLengthDesc = function() {
    var array = this;
    var compareByLength =  function(a, b) {
        if (a.length > b.length)
            return -1;
        else if (a.length < b.length)
            return 1;
        else 
            return 0;
    };
    array.sort(compareByLength);
    return array;
}

Array.prototype.getFirst = function() {
    return this[0];
}


'xyzzy'
    .generateSubstrings()
    .filter(function(el){
            return el.isPalindrome();
        })
    .sortByLengthDesc()
    .getFirst()