app.js

document.getElementById("input").addEventListener("keyup", function () {
  const input = document.getElementById("input");
  const inputValue = input.value;
  if (inputValue <= 0) {
    document.location.reload(true);
  }

  if (inputValue <= 9) {
    for (let i = 1; i <= inputValue; i++) {
      const inputItem = document.createElement("input");
      inputItem.setAttribute("id", i);
      inputItem.placeholder = `Enter the Mark of subject ${i}`;
      inputItem.type = "number";
      const form = document.getElementById("form");
      form.appendChild(inputItem);
    }
  } else {
    alert("You cannot take more than 10 courses");
  }
});

document.getElementById("btn").addEventListener("click", function () {
  const inputsValue = document.getElementById("input").value;
  let sum = 0;
  let gpa;
  for (let i = 1; i <= inputsValue; i++) {
    let result = document.getElementById(i);
    let resultValue = result.value;

    if (resultValue >= 80 && resultValue <= 100) {
      gpa = 4.0 * 3.0;
    } else if (resultValue >= 75 && resultValue <= 79) {
      gpa = 3.75 * 3.0;
    } else if (resultValue >= 70 && resultValue <= 74) {
      gpa = 3.5 * 3.0;
    } else if (resultValue >= 65 && resultValue <= 69) {
      gpa = 3.25 * 3.0;
    } else if (resultValue >= 60 && resultValue <= 64) {
      gpa = 3.0 * 3.0;
    } else if (resultValue >= 55 && resultValue <= 59) {
      gpa = 2.75 * 3.0;
    } else if (resultValue >= 50 && resultValue <= 54) {
      gpa = 2.5 * 3.0;
    } else if (resultValue >= 45 && resultValue <= 49) {
      gpa = 2.25 * 3.0;
    } else if (resultValue >= 40 && resultValue <= 44) {
      gpa = 2.0 * 3.0;
    } else if (resultValue === "") {
      Swal.fire({
        icon: "error",
        title: "Oops.. Input filed empty.",
        text: "Please fill up the all input filed!",
      });
      return;
    } else if (resultValue < 0) {
      Swal.fire({
        icon: "error",
        title: "Oops... You entered negative marks.",
        text: "Please Enter positive marks!",
      });
      return;
    } else if (resultValue > 100) {
      Swal.fire({
        icon: "error",
        title: "Oops...  Marks greater than 100",
        text: "Marks cannot be more than 100!",
      });
      return;
    } else {
      gpa = 0;
    }
    sum = sum + gpa;
  }
  let finalGpa = sum / (inputsValue * 3);

  if (inputsValue > 0) {
    document.getElementById("result-text").innerText = "Your GPA is = ";
    document.getElementById("results").innerText = finalGpa.toFixed(3);
  } else {
    alert("Your input number is negative or empty");
  }
});