JavaScript Range function

Первый вариант

if(!Array.indexOf){
    Array.prototype.indexOf = function (obj) {
        for (var i=0; i<this.length; i++) {
            if (this[i] == obj) {
                return i;
            }
        }
    }
}

function range(begin, end, step){
    var rangeArray = []
       , rangeString = 'abcdefghijklmnopqrstuvwxyz';
    if (Object.prototype.toString.call(begin) == '[object Number]') {
        rangeArray[0] = begin;
        step = step || 1;
        while (begin + step <= end) {
            rangeArray[rangeArray.length] = begin += step;
        }
    } else {
        if (begin === begin.toUpperCase()){
            end = end.toUpperCase();
            rangeString = rangeString.toUpperCase();
        }
        rangeString = rangeString.substring(rangeString.indexOf(begin), rangeString.indexOf(end) + 1);
        rangeArray = rangeString.split('');      
    }
    return rangeArray;
}


console.log(range(0, 10));
// [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

console.log(range(-100, 100, 20));
// [-100, -80, -60, -40, -20, 0, 20, 40, 60, 80, 100]

console.log(range('A', 'F'));
// ['A', 'B', 'C',' D', 'E', 'F')

console.log(range('m', 'r'));
// ['m', 'n', 'o', 'p', 'q', 'r']

Второй вариант

function range (start, end, step) {
    var range = []
      , typeofStart = typeof start
      , typeofEnd = typeof end;

    if (step === 0) {
        throw TypeError("Step cannot be zero.");
    }

    if (typeofStart == "undefined" || typeofEnd == "undefined") {
        throw TypeError("Must pass start and end arguments.");
    } else if (typeofStart != typeofEnd) {
        throw TypeError("Start and end arguments must be of same type.");
    }

    typeof step == "undefined" && (step = 1);

    if (end < start) {
        step = -step;
    }

    if (typeofStart == "number") {

        while (step > 0 ? end >= start : end <= start) {
            range.push(start);
            start += step;
        }

    } else if (typeofStart == "string") {

        if (start.length != 1 || end.length != 1) {
            throw TypeError("Only strings with one character are supported.");
        }

        start = start.charCodeAt(0);
        end = end.charCodeAt(0);

        while (step > 0 ? end >= start : end <= start) {
            range.push(String.fromCharCode(start));
            start += step;
        }

    } else {
        throw TypeError("Only string and number types are supported");
    }

    return range;

}

console.log(range("a", "z", 1));
console.log(range("Z", "A", 1));
console.log(range("A", "Z", 3));

console.log(range(0, 25, 1));
console.log(range(0, 25, 5));
console.log(range(20, 5, 5));