Validate 11 Digits in JavaScript

Question

Might be a simple question, but I can't find an answer that fits this bit of code :(

I need to validate a phone number to have EXACTLY 11 digits (no letters)

 function validateForm3() {
 var x=document.forms["booking"]["number"].value;
if (x==null || x=="")
 {
 alert("Please fill in 11 numbers");
 return false;
 }
 var x=document.forms["booking"]["email"].value;
if (x.indexOf("@")=== -1)
 {
 alert("Please enter a valid email");
 return false;
 }
}

I can't really change the structure of this, so it needs to fit into this bit of code :( any suggestions or answers is greatly appeciated :)

• Rabiani: YOU ARE ALL AMAZING! THANK YOU!

Answer 1

Use regexp.test:

if (! /^[0-9]{11}$/.test(x)) {
 alert("Please input exactly 11 numbers!");
 return false;
}

Note that you're intentionally excluding a lot of phone numbers, including international ones or alternative writing styles of phone numbers you could reach. You should really just test for /^\+?[0-9]+$/.

Answer 2

if (!/^\d{11}$/.test(x)) 
 alert('These are not 11 digits!');
else 
 alert('Passed!');

Try it http://jsfiddle.net/LKAPN/1/

Answer 3

Use regex:

"1234".match(/^\d{4}$/);

Explanation:

^ - matches the beginning of the string
\d - matches one digit
{4} - tells that we want four digits (you want thirteen then)
$ - matches the end of the string

See https://developer.mozilla.org/en/JavaScript/Guide/Regular_Expressions for further reading.

Answer 4

You can use regex for that:

var str = '12345678900';
if (str.match(/^\d{11}$/)) {
 // Valid
}

Answer 5

Maybe something like:

if (x.length == 11 && +x == x)

Answer 6

kinda hacky, but you could do:

if(x.length==11)
{
 for (var i=0; i<x.length; i++)
 {
 if (parseInt(x[i])!=x[i])
 {
 alert("only enter numbers!");
 }
 }
}
else
{
 alert("must enter 11 digits!");
}

• JKing: haha, of course I come up with a semi-convoluted method, completely ignoring regexp... hint: unless you're afraid of regexp for some reason, it's probably best to do that.

Answer 7

You can the use regular expression:

\d{11}

However, you probably also want to strip whitespace:

var isElevenNumbers = (/^\d{11}$/m.test(mynumber.replace(/\s]/g, '')));

And you may want to strip more for internation numbers, e.g. [phone]

var isElevenNumbers = (/^\d{11}$/m.test(mynumber.replace(/[\s\+\-]/g, '')));

where 'mynumber' is your variable holding the value.

Answer 8

Steven Levithan has a very useful excerpt on Regexps that validate North American as well as international phone numbers at http://blog.stevenlevithan.com/archives/validate-phone-number .

That page is excerpted from his book Regular Expressions Cookbook (O'Reilly, 2009)