Regular expression to check all digits the same or not

Question

Regular expression to check all digits the same or not

I have an input field that takes 12 digits. I want to throw an error when the user enters 12 digits of the same number. At least one number must be different.

For instance,

   111111111111 - Error

   111111111112 - Ok

   123456789012 - Ok

I tried this (but I want to invert the given regular expression)

var pattern = "^([0-9])\\1{3}$";
var str = "5555";
pattern = new RegExp(pattern);
if(!pattern.test(str))
{
    alert('Error');
}
else
{
    alert('Valid');
}