Turns an array of items into a String of items separated by middleJoiner and endJoiner

listJoiner.js

/*
var fruits = ['apple', 'orange', 'banana', 'pear'],
    middleJoiner = ', ',
    endJoiner = ' and ',
    result = listJoiner(fruits, middleJoiner, endJoiner);
*/
// result will be this string: 'apple, orange, banana and pear'

//Iterative way
function listJoinerIter(elems, middleJoiner, endJoiner) {
    var res = '', i;
    if(elems.isArray() && elems.length > 0) {
        for(i = 0; i < elems.length; i++) {
            res += elems[i];
            if(i === elems.length - 2) {
                res += endJoiner;
            } else if(elems.length > 1 && i < elems.length - 1) {
                res += middleJoiner;
            }
        }
    }
    return res;
}

//Recursvive way
function listJoinerRec(elems, middleJoiner, endJoiner) {
    if(elems.length === 0 || !elems.isArray()) {
        return '';
    } else if(elems.length === 1) {
        return elems[0];
    } else if(elems.length === 2) {
        return elems[0] + endJoiner + elems[1];
    } else {
        return elems[0] + middleJoiner + listJoiner(elems.shift(), middleJoiner, endJoiner);
    }
}