function addStuff() {
    var total = 0;
    for (var ii = 0; ii < arguments.length; ii++) {
        //Not only does this iterate through arguments, it uses the + to force addition instead of concatenation
        total += +arguments[ii];
    }
    return total;
}

Pass as many arguments as you wish. You can access them in the arguments array.

Umlimited arguments to function

JavaScript