Regular Expression in JavaScript for valid Domain Name

Question

I am having JavaScript as follows

function DomainValidation() {
        var val = document.getElementById('<%=txtDomainName.ClientID %>').value;
        if (/^[a-zA-Z0-9][a-zA-Z0-9-]{1,61}[a-zA-Z0-9](?:\.[a-zA-Z]{2,})+$/.test(val)) {
            return true;
        }
        else {
            alert("Enter Valid Domain Name");
            return false;
        }
    }

for checking the valid domain name. It is working fine except when I try to enter the domain name with only two character it is not accepting. Since I have no idea of using Regular Expression, so wanna know where I should make change so that it accept domain name with only two characters also.

Note:- Before marking this a duplicate and showing me this I would like to inform that the above script is working fine but I want it to accept the domain name with only two characters too.

Can you provide an example of a two-character domain name that you consider valid? — 200_success
– 200_success, Commented Dec 28, 2015 at 5:38
Did you try entering the title of your question into a search engine? I did, and the first four hits came from this very site. — miken32
– miken32, Commented Dec 28, 2015 at 5:39
may be u guys dint read question carefully. I clearly mentioned that its working fine except for domain name with 2 character — Naved Ansari
– Naved Ansari, Commented Dec 28, 2015 at 5:41
@miken32 may be you should try adding domain name xy.com using the script that is mentioned in your provided link — Naved Ansari
– Naved Ansari, Commented Dec 28, 2015 at 5:43

Avinash Raj · Accepted Answer · 2015-12-28 05:46:58Z

5

Just change {1,61} to {0,61}, so that it won't except the middle character.

^[a-zA-Z0-9][a-zA-Z0-9-]{0,61}[a-zA-Z0-9](?:\.[a-zA-Z]{2,})+$

DEMO

answered Dec 28, 2015 at 5:46

Avinash Raj

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3 Comments

famfamfam Over a year ago

failed with google.com

Avinash Raj Over a year ago

where? regex101.com/r/TbKaUB/1

famfamfam Over a year ago

yes, https://regex101.com/r/sU2qC4/3, failed with https: //google .com

Olaawo Oluwapelumi · Accepted Answer · 2022-11-20 01:12:34Z

1

Domain names can be tricky,

To support domain names like t.co you can use the below RegExp

^(?!-)[A-Za-z0-9-]+([-.]{1}[a-z0-9]+)*.[A-Za-z]{2,6}$

So you can pass the sample domain as first argument to the function below and it is expected to return true if the input is a valid domain and false otherwise.

const isValidDomainName = (supposedDomainName) => {
  return /^(?!-)[A-Za-z0-9-]+([\-\.]{1}[a-z0-9]+)*\.[A-Za-z]{2,6}$/i.test(
    supposedDomainName
  );
};

answered Nov 20, 2022 at 1:12

Olaawo Oluwapelumi

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