How to check the given random number is not in descending order?

I have generated a 4 digit random number, Where the random number should not be in descending order. It should not be like **7654 **.

Code:

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

This code just compares first and second digits and gives an **alert message
**. Could someone please help?

Thanks

I’ve tried to generate a random number, which should not be in a descending order. But, it didn’t work.

>Solution :

1. If you want to use only 4 digits, better to limit max number to 9999.
2. You can break iteration at the first case, when next digit bigger then previous.

    function descendingOrder(n) {
        let num = n.toString();
        var i = 0;
        while (i<=num.length) {
            if (num.substr(i) < num.substr(i+1)) {
                alert('This pattern can be used');
                return parseInt(n);
            } 
            i++;
        }
        alert('This pattern cannot be used');
    }
    descendingOrder(Math.floor(1000 + Math.random() * 8999));