How do I close a prompt upon clicking cancel in JS?

I cannot for the life of me figure out how to close the prompt altogether upon pressing cancel in my code for a guessing game. I’ve tried several things, but each time either the code ignores what I’m trying to do, or ends in an error. Here’s the code in question:

let numGuess = prompt (`Guess the number I am thinking of (between 1 and 10):`);
let num = (4);

let numTries = 1

console.log(numGuess);

numGuess = parseInt(numGuess)

if (prompt == null) {

alert (`Press F5 to play again.`) 


}
if (numGuess === num) {

  alert (`Correct! You guessed the number in 1 try! Press F5 to play again.`);

}

else while ((numGuess !== num) && (numTries <3))

{

  numTries = numTries++

  alert (`Incorrect guess. Try again.`)

}