How to check if the elements of an array are identical in javascript (more than 2 elements)

Question

I am trying to make sure that a phone# is not all identical characters, example 1111111111 The code I am using works but there has to be a cleaner way. I've tried loops but that only compares two consecutive characters at a time. This is what I am using now:

if (MainPhone.value != "")
            {               
                if ((MainPhone.value == 1111111111) || (MainPhone.value == 2222222222) || (MainPhone.value == 3333333333) || (MainPhone.value == 4444444444) || (MainPhone.value == 5555555555) || (MainPhone.value == 6666666666) || (MainPhone.value == 7777777777) || (MainPhone.value == 8888888888) || (MainPhone.value == 9999999999) || (MainPhone.value == 0000000000))
                {
                window.alert("Phone Number is Invalid");
                MainPhone.focus();
                return false;
                }
            }

I found this recommendation for someone else' question but could not get it to work.

var dup = MainPhone.value.split('');
if all(dup == dup(1))

Answer 1

I would try something like this:

var phone = '11111211';
var digits = phone.split('').sort();
var test = digits[0] == digits[digits.length - 1];

Simply sort the array and compare first and last element..

Answer 2

You can use a regular expression like this to check if all characters are the same:

^(.)\1*$

Example:

var phone = '11111111';

if (/^(.)\1*$/.test(phone)) {
  alert('All the same.');
}

Demo: http://jsfiddle.net/Guffa/3V5en/

---

Explanation of the regular expression:

^   = matches start of the string
(.) = captures one character
\1  = matches the first capture
*   = zero or more times
$   = matches end of the string

So, it captures the first character, and matches the rest of the characters if they are the same.