check if number is single digit javascript code example

Example: javascript to check each digit in the number

function test_same_digit(num) {
  const first = num % 10;
  while (num) {
    if (num % 10 !== first) return false;
num = Math.floor(num / 10);
  }
  return true
}

console.log(test_same_digit(1234));
console.log(test_same_digit(1111));
console.log(test_same_digit(22222222));