} while ( ! correctGuess ) ... ?

The loop always checks whatever the condition's current boolean value is since the original value may have changed since the last run through the loop. Here are a couple of scenarios of how this particular loop could run. (Keep in mind that the reason why we set correctGuess to false before we start looping is because the user cannot have answered correctly before they ever submit a guess.)

User correctly guesses random number on first try

1. Function prompts user for a guess.
2. User guesses correctly, which changes the current value of correctGuess to true.
3. Loop checks whether !correctGuess is true. If the condition (not the variable correctGuess) is true, the loop will run again. But if the condition is false, then the function will exit the loop.
4. Because !correctGuess is now false, the function exits the loop.

User correctly guesses random number on nth try

1. Function prompts user for a guess.
2. User guesses incorrectly, so the current value of correctGuess continues to be false.
3. Loop checks whether !correctGuess is true. Again, if the condition (not the variable correctGuess) is true, the loop will run again. But if the condition is false, then the function will exit the loop.
4. Because !correctGuess is still true, the function steps through the loop again.
5. Repeat steps 1-4 until the user guesses correctly, which changes the current value of correctGuess to true.
6. Now that !correctGuess is false, the function exits the loop.

If the not operator is throwing you off, you can use the condition correctGuess === false, which will yield the same result.

You are correct that the variable is available to the scope of the loop. But the "!" character is the "NOT" operator, so "while (! correctGuess)" means to loop while "correctGuess" is not true (or while it is false).

Still confused.. isn't the assigned value of correctGuess false? The variable was created var correctGuess = false;. It seems the "NOT" operator would make ! correctGuess loop while correctGuess is not false (or while it is true).

Both while and do-while loops execute while the supplied condition is true. Since correctGuess is initially assigned the value of false, !correctGuess evaluates to true until the user enters a guess that matches the random number, at which point correctGuess is set to true inside the loop, and !correctGuess evaluates to false, which causes the program to exit the loop.

I'm on the verge of understanding...

1st off, it seems like there's some discrepancy between Steven and Tiff's answers- does the NOT operator cause the variable to be checked against the original assignment or no?

Assuming it does, my confusion is this- Tiff says,

Both while and do-while loops execute while the supplied condition is true. Since correctGuess is initially assigned the value of false, !correctGuess evaluates to true.

This is where I get lost. If the loop will run until correctGuess is true, and correctGuess is assigned a false value, wouldn't !correctGuess be true and stop the loop before it even gets started?

(For reference, a screenshot of this problem can be seen here- https://imgur.com/a/26Vt3)

The "NOT" operator only gives the opposite of the current value. Variables don't "remember" what value was originally assigned to them.

And you are correct that if "correctGuess" is assigned a false value, then "!correctGuess" will be true. But this does not stop the loop, instead it allows the loop to repeat. The loop will only stop when "!correctGuess" is false (meaning just "correctGuess" is true).

Ok... so how is the current value of the variable determined if not by what was originally assigned? Is it redefined within the do/while statement? Does this mean that the content associated with the 'while' portion is operating within the scope of the do/while statement, even though it falls outside the braces? If so, here's a stupid question- what's the point in assigning the original value in the first place?

Not trying to be dense, thanks for your patience.