<!-- The JavaScript Source!! http://javascript.internet.com -->

<!-- Begin

function emailCheck (emailStr) {

var rv = '';

/* The following variable tells the rest of the function whether or not

to verify that the address ends in a two-letter country or well-known

TLD.  1 means check it, 0 means don't. */

var checkTLD=1;

/* The following is the list of known TLDs that an e-mail address must end with. */

var knownDomsPat=/^(com|net|org|edu|int|mil|gov|arpa|biz|aero|name|coop|info|pro|museum)$/;

/* The following pattern is used to check if the entered e-mail address

fits the user@domain format.  It also is used to separate the username

from the domain. */

var emailPat=/^(.+)@(.+)$/;

/* The following string represents the pattern for matching all special

characters.  We don't want to allow special characters in the address. 

These characters include ( ) < > @ , ; : \ " . [ ] */

var specialChars="\\(\\)><@,;:\\\\\\\"\\.\\[\\]";



/* The following string represents the range of characters allowed in a 

username or domainname.  It really states which chars aren't allowed.*/

var validChars="\[^\\s" + specialChars + "\]";



/* The following pattern applies if the "user" is a quoted string (in

which case, there are no rules about which characters are allowed

and which aren't; anything goes).  E.g. "jiminy cricket"@disney.com

is a legal e-mail address. */



var quotedUser="(\"[^\"]*\")";



/* The following pattern applies for domains that are IP addresses,

rather than symbolic names.  E.g. joe@[123.124.233.4] is a legal

e-mail address. NOTE: The square brackets are required. */

var ipDomainPat=/^\[(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})\]$/;



/* The following string represents an atom (basically a series of non-special characters.) */



var atom=validChars + '+';



/* The following string represents one word in the typical username.

For example, in john.doe@somewhere.com, john and doe are words.

Basically, a word is either an atom or quoted string. */



var word="(" + atom + "|" + quotedUser + ")";



// The following pattern describes the structure of the user



var userPat=new RegExp("^" + word + "(\\." + word + ")*$");



/* The following pattern describes the structure of a normal symbolic

domain, as opposed to ipDomainPat, shown above. */

var domainPat=new RegExp("^" + atom + "(\\." + atom +")*$");



/* Finally, let's start trying to figure out if the supplied address is valid. */

/* Begin with the coarse pattern to simply break up user@domain into

different pieces that are easy to analyze. */



var matchArray=emailStr.match(emailPat);

if (matchArray==null) {



/* Too many/few @'s or something; basically, this address doesn't

even fit the general mould of a valid e-mail address. */

rv = "E-mail address is incorrect.";

return rv;

}



var user=matchArray[1];

var domain=matchArray[2];

// Start by checking that only basic ASCII characters are in the strings (0-127).

for (i=0; i<user.length; i++) {

if (user.charCodeAt(i)>127) {

	rv = "E-mail address is incorrect.";
	return rv;
   }





}

for (i=0; i<domain.length; i++) {

	if (domain.charCodeAt(i)>127) {

	rv = "E-mail address is incorrect.";
	return rv;
   }

}

// See if "user" is valid 

if (user.match(userPat)==null) {

// user is not valid



rv = "The username doesn't seem to be valid.";
return rv;
}

/* if the e-mail address is at an IP address (as opposed to a symbolic

host name) make sure the IP address is valid. */

var IPArray=domain.match(ipDomainPat);

if (IPArray!=null) {

// this is an IP address

for (var i=1;i<=4;i++) {

if (IPArray[i]>255) {

rv = "E-mail address is incorrect.";
return rv;
   }

}



return rv;

}



// Domain is symbolic name.  Check if it's valid.

var atomPat=new RegExp("^" + atom + "$");

var domArr=domain.split(".");

var len=domArr.length;

for (i=0;i<len;i++) {

if (domArr[i].search(atomPat)==-1) {

rv = "E-mail address is incorrect.";

return rv;

   }

}



/* domain name seems valid, but now make sure that it ends in a

known top-level domain (like com, edu, gov) or a two-letter word,

representing country (uk, nl), and that there's a hostname preceding 

the domain or country. */

if (checkTLD && domArr[domArr.length-1].length!=2 && 

domArr[domArr.length-1].search(knownDomsPat)==-1) {

rv = "E-mail address is incorrect.";

return rv;

}





// Make sure there's a host name preceding the domain.

if (len<2) {

rv = "E-mail address is incorrect.";

return rv;

}



// If we've gotten this far, everything's valid!

return rv;

}

//  End -->