Can't understand why 4?

Question

var a=[9,5,3];
for (var i = 0; i <3; i++) {
a[0]%=a[i];
a[0]+=a[2];
}
document.write(a[0])

Answer 1

The output is 3:

1. iteration, i = 0:
9%9=0
0+3=3=a[0]

2. iteration, i=1
3%5=3
a[0]=3+3=6

3. iterarion, i=2
6%3=0
a[0]=0+3=3 -> output 3.

Answer 2

@shaldem
This would explain the output 4 ^^

Answer 3

Hmm... To me it looks more like 3.

It goes through the iteration and assigns stuff to a[0].
1. a[0] is 9, initially
2. a[0] = a[0] % a[0] = 0
3. a[0] = a[0] + 3 = 3
4. a[0] = a[0] % 5 = 3
5. a[0] = a[0] + 3 = 6
6. a[0] = a[0] % 3 = 0
7. a[0] = a[0] + 3 = 3

3

Answer 4

As I remember in challange question was other cicle, there was for(var i=1;i<3;i++)?