<SCRIPT LANGUAGE="JavaScript"> <!-- The JavaScript Source!! http://javascript.internet.com --> <!-- V1.1.3: Sandeep V. Tamhankar (stamhankar@hotmail.com) --> <!-- Changes: /* 1.1.4: Fixed a bug where upper ASCII characters (i.e. accented letters international characters) were allowed. 1.1.3: Added the restriction to only accept addresses ending in two letters (interpreted to be a country code) or one of the known TLDs (com, net, org, edu, int, mil, gov, arpa), including the new ones (biz, aero, name, coop, info, pro, museum). One can easily update the list (if ICANN adds even more TLDs in the future) by updating the knownDomsPat variable near the top of the function. Also, I added a variable at the top of the function that determines whether or not TLDs should be checked at all. This is good if you are using this function internally (i.e. intranet site) where hostnames don't have to conform to W3C standards and thus internal organization e-mail addresses don't have to either. Changed some of the logic so that the function will work properly with Netscape 6. 1.1.2: Fixed a bug where trailing . in e-mail address was passing (the bug is actually in the weak regexp engine of the browser; I simplified the regexps to make it work). 1.1.1: Removed restriction that countries must be preceded by a domain, so abc@host.uk is now legal. However, there's still the restriction that an address must end in a two or three letter word. 1.1: Rewrote most of the function to conform more closely to RFC 822. 1.0: Original */ // --> <!-- Begin function emailCheck (emailStr) { /* 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 +")*$"); /* Finally, let's start trying to figure out if the supplied address is valid. */ /* Begin with the coarse pattern to simply break up user@domain into different pieces that are easy to analyze. */ var matchArray=emailStr.match(emailPat); if (matchArray==null) { /* Too many/few @'s or something; basically, this address doesn't even fit the general mould of a valid e-mail address. */ alert("Email address seems incorrect (check @ and .'s)"); return false; } var user=matchArray[1]; var domain=matchArray[2]; // Start by checking that only basic ASCII characters are in the strings (0-127). for (i=0; i<user.length; i++) { if (user.charCodeAt(i)>127) { alert("Ths username contains invalid characters."); return false; } } for (i=0; i<domain.length; i++) { if (domain.charCodeAt(i)>127) { alert("Ths domain name contains invalid characters."); return false; } } // See if "user" is valid if (user.match(userPat)==null) { // user is not valid alert("The username doesn't seem to be valid."); return false; } /* if the e-mail address is at an IP address (as opposed to a symbolic host name) make sure the IP address is valid. */ var IPArray=domain.match(ipDomainPat); if (IPArray!=null) { // this is an IP address for (var i=1;i<=4;i++) { if (IPArray[i]>255) { alert("Destination IP address is invalid!"); return false; } } return true; } // Domain is symbolic name. Check if it's valid. var atomPat=new RegExp("^" + atom + "$"); var domArr=domain.split("."); var len=domArr.length; for (i=0;i<len;i++) { if (domArr[i].search(atomPat)==-1) { alert("The domain name does not seem to be valid."); return false; } } /* 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) { alert("The address must end in a well-known domain or two letter " + "country."); return false; } // Make sure there's a host name preceding the domain. if (len<2) { alert("This address is missing a hostname!"); return false; } // If we've gotten this far, everything's valid! return true; } // End --> </script>

<form name=emailform onSubmit="return emailCheck(this.email.value)"> Your Email Address: <input type=text name="email" size="20"> <input type=submit value="Submit"> </form>