what does ++ do?

Answer 1

increment your number by 1.

Answer 2

it adds one to the number.

for (i=0;i <10;i++){
alert (i);
}

i++ is a shortcut that means i=i+1
therefore the value of i increases during the loop.

Answer 3

just let x+1

Answer 4

i++ is post increment and ++i is pre increment.Suppose var a=5;a++;
Here post increment the value of 5 is assigned to a and incremented by 1; whereas if there was ++a instead of a++ , pre increment the value of a is first incremented and then assigned to a