Number of Students Unable to Eat Lunch LeetCode solution in JavaScript

1
var countStudents = function (students, sandwiches) {
2
  while (students.length > 0 && students.indexOf(sandwiches[0]) != -1) {
3
    if (students[0] == sandwiches[0]) {
4
      students.shift();
5
      sandwiches.shift();
6
    } else students.push(students.shift());
7
  }
8
  return students.length;
9
};