JavaScript sort multiple array

Suppose I have this data

Name	Mark
John	76
Jack	55
Dani	90

and for the grade

Marks	Grade
100-80	A
79 – 60	B
59 – 40	C

suppose i declare the script as

 let data = [
  [John, 76],
  [Jack, 55],
  [Dani, 90]
];

The program should assign the grade with the corresponding mark, how do I sort the grade since we know we cant change the index for mark as usual because each mark assign to different student? The output should display all data in descending order as

Name	Mark	Grade
Dani	90	A
John	76	B
Jack	55	C

Answer

I would break it up into different functions so that you can handle each task separately. Then you can combine them to produce your desired result, like this:

const grades = [
  ['A', 80],
  ['B', 60],
  ['C', 40],
];

function getGrade (mark) {
  for (const [grade, minMark] of grades) {
    if (mark < minMark) continue;
    return grade;
  }
  return 'F'; // use minimum grade as default if mark is too low
}

function mapToObject ([name, mark]) {
  return {grade: getGrade(mark), name, mark};
}

function sortByHighestMark (a, b) {
  return b.mark - a.mark;
}

const data = [
  ['John', 76],
  ['Jack', 55],
  ['Dani', 90]
];

const result = data.map(mapToObject).sort(sortByHighestMark);
console.log(result);

// and data is unmodified:
console.log(data);