Set with intersection

jssetintersection.js

/**
* Set intersect
* The algorithm is provided by Ophir LOJKINE. I modified it to work for sets.
* @author Ophir LOJKINE
* https://gist.github.com/lovasoa/3361645
* @author Bijan Vakili
*/
Set.prototype.intersect = function() {
    var i, all, shortest, nShortest, n, len, ret = [], obj={}, nOthers;
    arguments[arguments.length++] = this;
    nOthers = arguments.length-1;
    nShortest = arguments[0].size;
    shortest = 0;

    for (i=0; i<=nOthers; i++){
        n = arguments[i].size;
        console.log("n: " + n);
        if (n<nShortest) {
            shortest = i;
            nShortest = n;
        }
    }
    for (i=0; i<=nOthers; i++) {
        n = (i===shortest)?0:(i||shortest); //Read the shortest array first. Read the first array instead of the shortest
        len = arguments[n].size;
        console.log("len " + len);
        arr = Array.from(arguments[n]);
        for (var j=0; j<len; j++) {
            var elem = arr[j];
            if(obj[elem] === i-1) {
                if(i === nOthers) {
                    ret.push(elem);
                    obj[elem]=0;
                } else {
                    obj[elem]=i;
                }
            } else if (i===0) {
                obj[elem]=0;
            }
        }
    }
    return ret;
};

/** Begin Test **/

$(document).ready(function () {


function logIt(x) {
    $("#result-question3").append(x + "<br />");
    console.log(x);
}

var x = new Set();
x.add("1");
x.add("2");
x.add("3");
x.add("7");

var y = new Set();
y.add("1");
y.add("5");
y.add("7");

var z = new Set();
z.add("1");
z.add("2");
z.add("3");
z.add("7");

logIt("Set x : " + JSON.stringify(Array.from(x)));
logIt("Set y : " + JSON.stringify(Array.from(y)));
logIt("Set z : " + JSON.stringify(Array.from(z)));

result = x.intersect(y, z);
logIt("Intersection: " + JSON.stringify(result));

});