let cancelGridCreation = false;

    let waitingForQualifyingAnswer = true;

    let answer = prompt('Please enter the number of rows/columns, as a positive integer:', '16');

    let gridSize = parseFloat(answer, 10);

    console.log('size entered: ' + gridSize);

    while (waitingForQualifyingAnswer === true) {

      console.log('top of while');

      if (answer == null || answer == "") {

        console.log('prompt - canceled');

        cancelGridCreation = true;

        waitingForQualifyingAnswer = false;

      } else if (typeof gridSize === 'number' && gridSize % 1 === 0 && gridSize > 0) {

        console.log('prompt - good answer: ' + gridSize);

        waitingForQualifyingAnswer = false;

      } else {

        console.log('prompt - BAD answer: ' + gridSize);

        answer = prompt('Incorrect format entered.  Please enter the number of rows/columns, as a positive integer:', '16');

        gridSize = parseFloat(answer, 10);

        console.log('new size entered: ' + gridSize);

      }

      console.log('end of while');

    }

​

console.log('done:');

console.log(gridSize);