Does anyone see any errors or potential issues with this JS code?

I paused the video to see if I could complete the task and I came up with the following code. It's shorter than the way the instructor answered it in the video. It runs just fine. But does anyone see any potential errors with it that I don't see?

var randomNumber = getRandomNumber(10); var guess; var guessCount = 0;

function getRandomNumber( upper ) { var num = Math.floor(Math.random() * upper) + 1; return num; }

do { guess = prompt("Guess a number between 1 and 10."); guessCount += 1; } while ( parseInt(guess) !== randomNumber)

document.write("You guessed it! The random number was " + randomNumber + " and it took you " + guess + " tries to get it right. Well done!");