else if — หลายทาง

const score = 72;
let grade;

if (score >= 80) {
  grade = "A";
} else if (score >= 70) {
  grade = "B";
} else if (score >= 60) {
  grade = "C";
} else if (score >= 50) {
  grade = "D";
} else {
  grade = "F";
}

console.log(grade);