Question

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Validate email address in Javascript?

I am trying to use this javascript to check for a valid email, but what I don’t need it to do is check to see if the field is blank in the form in case someone doesn’t have an email address (don’t ask).

function validate_email(field,alerttxt)
{
with (field)
{
apos=value.indexOf("@");
dotpos=value.lastIndexOf(".");
if (apos<1||dotpos-apos<2) 
  {alert(alerttxt);return false;}
else {return true;}
}
}

function validate_form(thisform)
{
with (thisform)
{
  if (validate_email(email,"Not a valid e-mail address.")==false)
  {email.focus();return false;}
}
}

I tried to adjust the apos<1 to less than 1 or nothing at all and that didn’t seem to work.

Answer 1

Just check whether it is empty, and otherwise apply your email regex/validation function on it.

Also, you should a) not use with and b) not alert from the test function.

function test_email(address) {
    var atpos = address.indexOf("@"),
        dotpos = address.lastIndexOf(".");
    if (atpos < 1) // "@" at position 0 or not found (-1)
        return false;
    if (dotpos-atpos < 2) // last "." before position 2 or not found (-1)
        return false;
    if (atpos > dotpos) // last "." before the "@"
        return false;
    return true;
}

function validate_form(thisform) {
    var input = thisform.email;
    if (input.value) // != ""
        if (!test_email(input.value)) {
            alert("Not a valid e-mail address.");
            email.focus();
            return false;
        }
}