How the ans is 12 ?

Question

var b=0;
for(var i=0;i<=2;i++){
for(var j=0;j<=3;j++){
b++}
}
alert(b);

Answer 1

Outer loop runs the inner loop 3 times. Inner loop runs the b increment 4 times.

b is incremented from 0 by 3 * 4 times, which is +12.

Answer 2

You can put
console.log(i, j, b)
in the line after b to better understand what happens

Answer 3

The reason as to why the answer is 12 is due to the second for loop being inside a for loop. The first loop is called with the variable i going from 0 - 2 because you used <=. Once this is called, the second for loop is called with the variable j going from 0 - 3 because you used <=. So, the b++ gets called 4 times from the second for loop and once that finishes, the first loop gets called again but now i is 1. This repeats for when i becomes 2 but then it ends. This results in the b++ getting called 4 times for the second loop and the second loop getting called 3 times from the first loop. 4 x 3 = 12. That is how the answer is 12. If you used < instead of <=, the answer would be 6.

Answer 4

Thanks to all