Why 10?

Question

var a=0;
for (var i = 0; i < 3; i++) {
for (var j = 3; j > 0; j--) {
++a;
}
}

document.write(++a)

Answer 1

1. i = 0; i < 3 true; i = 0 + 1
j = 3; j > 0 true; j = 3 - 1
a = 0 + 1
j = 2; j > 0 true; j = 2 - 1
a = 1 + 1
j = 1; j > 0 true; j = 1 - 1
a = 2 + 1
j = 0; j > 0 false ..... stop loop
2. i = 1; i < 3 true; i = 1 + 1
j = 3; j > 0 true; j = 3 - 1
a = 3 + 1
j = 2; j > 0 true; j = 2 - 1
a = 4 + 1
j = 1; j > 0 true; j = 1 - 1
a = 5 + 1
j = 0; j > 0 false ..... stop loop
3. i = 2; i < 3 true; i = 2 + 1
j = 3; j > 0 true; j = 3 - 1
a = 6 + 1
j = 2; j > 0 true; j = 2 - 1
a = 7 + 1
j = 1; j > 0 true; j = 1 - 1
a = 8 + 1
j = 0; j > 0 false ..... stop loop
4. i = 3; i < 3 false ..... stop loop

document.write(a++) 9 + 1
OUTPUT 10

Kristina this is my quiz on Quiz Factory

Answer 2

1. Iteration, i=0
inner loop runs 3 times, so a=3
2. Iteration, i= 1
a=6
3. Iteration, i=2
a=9

++a results in 10, output 10.

Answer 3

As @Kuba said:
The first loop is called outer loop.
It immediately executes the inner loop, until the inner loop ends all iterations after 3 times running.
The outer loop still has 2 iterations to execute.
So... it immediately runs the inner loop, which runs 3 times again.
Then the outer loop runs the last iteration...
and immediately runs the inner loop - 3 times.
Then the outer loop is completed.

Answer 4

@Kuba You won the race ;)

Answer 5

It goes 3 iterations by 3, so 9 altogether.
(++a means increase by 1)

After that, you ask to increase by 1 one more time and then print.

9+1=10, so... ;)

Answer 6

Wrote a code, maybe it helps you...
https://code.sololearn.com/WdQR42E3EecP/?ref=app

Answer 7

You're welcome.

Answer 8

Those are nested loops. One of them iterates three times and within each iteration it triggers the inner one three times (each time!). So the inner loop is run nine times altogether. And its sole instruction is ++a which means (increase a by 1).

After the looping finishes, a equals 9.

In the end you ask to print out ++a, which means "print out a increased by 1". So a is increased by 1 (now it equals 10) and is printed on the screen.

Answer 9

@Tashi N woww that was some clear cut explanation can't get any better, I usually had an ideas of nested loops this takes it further thank you.

Answer 10

thx but we have a two loop why going up

Answer 11

thx so much

Answer 12

can't understand sorry