The Code

                    
                        //get starting values from the screen
//Controller Function

function getValues() {
  // get the values from the page
  let fizzValue = document.getElementById("fizzValue").value;
  let buzzValue = document.getElementById("buzzValue").value;
  let customValue = document.getElementById("customValue").value;

  // parse the values into integers
  fizzValue = parseInt(fizzValue);
  buzzValue = parseInt(buzzValue);
  customValue = parseInt(customValue);

  if (Number.isInteger(fizzValue) && Number.isInteger(buzzValue) && fizzValue > 0 && buzzValue > 0 && Number.isInteger(customValue)) {
    // generate the numbers based on user input
    let numbers = generateFizzBuzz(fizzValue, buzzValue, customValue);

    // display result on page
    displayFizzBuzz(numbers);
  } else {
    Swal.fire({
      icon: "error",
      title: "Oops...",
      text: "Only intergers and numbers greater than 0 are allowed for FizzBuzz!",
    });
  }
}

function generateFizzBuzz(fizzValue, buzzValue, customValue) {
  let fizzbuzz = [];
  let cap = customValue;

  for (let i = 1; i <= cap; i++) {
    if((i % fizzValue == 0) && (i % buzzValue == 0)){
      fizzbuzz.push('FizzBuzz');
    }
    else if(i % fizzValue == 0){
      fizzbuzz.push('Fizz')
    }
    else if(i % buzzValue == 0){
      fizzbuzz.push('Buzz')
    }    
    else{
      fizzbuzz.push(i);
    }
  }

  return fizzbuzz;
}

function displayFizzBuzz(numbers) {
  let className = "";
  let templateRows = "";

  for (let i = 0; i < numbers.length; i++) {
    let number = numbers[i];

    if (number == "FizzBuzz") {
      className = "FizzBuzz";
    } else if (number == "Fizz") {
      className = "Fizz";
    } else if (number == "Buzz") {
      className = "Buzz";
    } else {
      className = "";
    }

    if (i % 10 == 0) {
      templateRows += "";
    }

    templateRows += ` ${number} `;

    //An templateRows += `${number}`;

    if ((i + 1) % 10 == 0) {
      templateRows += "";
    }
  }

  document.getElementById("results").innerHTML = templateRows;
}