why this for loop output 3 with global variable

Question

explain me this code why for loop with global variable make output 3. if variable are put inside for loop or hoist above the undefined it gives 9
var i = 0,j = 0, count = 0;​
for(; i < 3; i++){    
for(; j < 3; j++){      
  count++;
  }
}
console.log(count)

Answer 1

It's because the second loop is executed only once instead of three times. When the second loop start for the first time, it will loop and incrament j until it has a value of 3. The j variable is a global variable, therefore it will stay there until the program ended. After the first loop, the loop will see that j variable has the value of 3, therefore it won't start again