JS Challenge

Question

I came across this question in JS challenge,

var a = 1,x;
x = ++a + ++a;
x+=a;
alert(x);

//output is 8

I would be really thankful if anyone explains this to me.

Answer 1

yes.
var a,x;
var a=1,x;
var a,x=1;
all true.

Answer 2

x=++a + ++a --> x=++1 + ++(++1)=2+ ++2=2+3=5 and a=3
×+=a // x=x+a=5+3=8

Answer 3

I didn't understand the first line var a= 1,x;
Are we assigning two values to one variable a?