How to validate domain name using regex?

Question

This is my code for validating domain name.

function frmValidate() {
    var val = document.frmDomin;
    if (/^[a-zA-Z0-9][a-zA-Z0-9-]{1,61}[a-zA-Z0-9]\.[a-zA-Z]{2,}$/.test(val.name.value)) {
    }
    else {
        alert("Enter Valid Domain Name");
        val.name.focus();
        return false;
    }
}

and

<form name="frmDomin" action="" method="post" onsubmit="return frmValidate();">
Domain Name : <input type="text" value="" id="name" name="name"  />
</form>

Now I entered http://devp1.tech.in and it alert the message. I want to enter sub domain also. How to change this? I should not get alert.

Answer 1

Try this:

^[a-zA-Z0-9][a-zA-Z0-9-]{1,61}[a-zA-Z0-9](?:\.[a-zA-Z]{2,})+$

Demo