studentGenerator.js

const r1 = require("readline").createInterface({
  input: process.stdin,
  output: process.stdout,
});

function awardGrades(score) {
  if (score > 79) {
    return "A";
  } else if (score >= 60 && score <= 79) {
    return "B";
  } else if (score >= 50 && score <= 59) {
    return "C";
  } else if (score >= 40 && score <= 49) {
    return "D";
  } else {
    return "E";
  }
}

r1.question("Enter student marks: ", function (input) {
  const mark = Number(input);

  if (isNaN(mark) || mark > 100 || mark < 0) {
    console.log("The marks you entered is not correct");
  } else {
    let grade = awardGrades(mark);
    console.log("The grade is " + grade);
  }

  r1.close();
});