Отправьте заголовок Хоста при доступе к IP-адресу в Firefox

var userEntry1 = Number(window.prompt("Enter in a number of your choice"));
var userEntry2 = Number(window.prompt("Enter in a number of your choice"));
var userEntry3 = Number(window.prompt("Enter in a number of your choice"));

function addNumb(userEntry1, userEntry2, userEntry3) {
    "use strict";
    var sum = userEntry1 + userEntry2 + userEntry3;
    return sum;       
}

function addNumb2() {
    "use strict";
    for (var i = 0, sum = 0; i < arguments.length; i++) {
        sum += Number(arguments[i]);
    }
    return sum;
}

console.log(addNumb(userEntry1, userEntry2, userEntry3));
console.log(addNumb2(userEntry1, userEntry2, userEntry3));