To check the repeating digits in a single number in JS

I used random function, to generate a 4 digit number.

The generated 4 digit random number should not be in the sequence of 1111, 2222, 3333, …. The generated random number could be of any number except 1111, 2222, 3333, 4444,..

I used the below approach,

But, i could get the repeating of digits using the below code. Could somebody please help.

function repeatingDigit(n) {
    let num = n.toString();
    for (var i = 0; i <= num.length; i++) {
       if (num.substr(i) == num.substr(++i)) {
            alert('This pattern can not be used');
        }
       else {
            return parseInt(n);
       }
     }
}
repeatingDigit(Math.floor(1000 + Math.random() * 9000));

Thank you.

>Solution :

You could just check if it’s divisible by 1111:

function repeatingDigit(n) {
    if (n % 1111 === 0) {
       alert('This pattern can not be used');
    }

    return n;
 }

repeatingDigit(Math.floor(1000 + Math.random() * 9000));