What is the answer and why? Thanks.

Think of variables as containers or boxes where you store things. The first line of code:

var initialScore = 8

says to create a box called initialScore and store an 8 in it. The second line of code:

initialScore = initialScore + 1

says to take initialScore out of it's box, add 1 to it and put the result back into the initialScore box. Thus initialScore will be 9 now. The third line of code:

var totalScore = initialScore

says to take the contents of initialScore (now 9), copy the value and place it into a new container called totalScore. The fourth line of code:

totalScore = ++initialScore 

says to take the value of initialScore and increment it by 1, then assign that back to totalScore. So initialScore was 9 and we added 1 to it to make it 10. Then we copied the value 10 and saved it to totalScore. After the 4th line of code both variables should have the value of 10.

i agree with the explanation of jonlunsford both will be equal to 10.

keep in mind there is a big difference between ++variable and variable++ ++variable will force the incrementation of the variable before you start using it in the line, whereas variable++ will cause the increment to be after you are done with the calculation on that line (more like deferred addition) example:

var sum = 20 var total = sum++ (will result in total to be 20 and sum will become 21 on the next line because the ++ will only fire after all calculations are done on this line)

however:

var total = ++sum (will result in total and sum to be 21 on this line and afterwards because the ++ before the variable will trigger the sum to increment first and then be assigned to total)

hope its clear! cheers.