SOURCE

var  a = [1,2,3];
a.name = "dajs";
for(var i in a)
{
    console.log(a[i]);
}

for(let o of a)
{
    console.log(o);
}

console.log(a.length);

let set = new Set([1,1,2,3,5,5,6,6,6,6]);
console.log(set.size);
console.log([...set]);
set.add(6);
console.log([...set]);


let b = [2,2,5,6,8,9,9,5,6];
let c = new Set(b);
console.log(c);

console.log(c.values())

var a1 = [1,2,5,6];
var b1 = [2,3,5,6];
var c1 = new Set(a1);
var c2 = new Set(b1);
var c3 = [...c1].filter(x => c2.has(x));
console.log(c3);
var c4 = [...c1].filter(x => !c2.has(x));
console.log(c4);