// JavaScript Document
// This code is used to verify e-mail address formatting
// Add the following code on the field where you collect the e-mail address 
// onBlur="emailOK(this.value)"

function checkEmail(emailAddr) {
	// this function checks for a well-formed e-mail address
	// in the format:
	// user@domain.com
	
	var i;
	
	// check for @
	i = emailAddr.indexOf("@");
	if (i == -1) {
		return false;
	}
	
	// separate the user name and domain
	var username = emailAddr.substring(0, i);
	var domain = emailAddr.substring(i + 1, emailAddr.length)

	// look for spaces at the beginning of the username
	i = 0;
	while ((username.substring(i, i + 1) == " ") && (i < username.length)) {
		i++;
	}
	// remove any found
	if (i > 0) {
		username = username.substring(i, username.length);
	}

	// look for spaces at the end of the domain
	i = domain.length - 1;
	while ((domain.substring(i, i + 1) == " ") && (i >= 0)) {
		i--;
	}
	// remove any found
	if (i < (domain.length - 1)) {
		domain = domain.substring(0, i + 1);
	}

	// make sure neither the username nor domain is blank
	if ((username == "") || (domain == "")) {
		return false;
	}
	
	// check for bad characters in the username
	var ch;
	for (i = 0; i < username.length; i++) {
		ch = (username.substring(i, i + 1)).toLowerCase();
		if (!(((ch >= "a") && (ch <= "z")) || 
			((ch >= "0") && (ch <= "9")) ||
			(ch == "_") || (ch == "-") || (ch == "."))) {
				return false;
		}
	}
	
	// check for bad characters in the domain
	for (i = 0; i < domain.length; i++) {
		ch = (domain.substring(i, i + 1)).toLowerCase();
		if (!(((ch >= "a") && (ch <= "z")) || 
			((ch >= "0") && (ch <= "9")) ||
			(ch == "_") || (ch == "-") || (ch == "."))) {
				return false;
		}
	}

	var aSuffix = new Array("com","edu","org","gov","mil","ca","net");
	var bFoundSuffix = false;
	i = 0;
	while (i < aSuffix.length) {
		if (("." + aSuffix[i]) == domain.substring(domain.length - aSuffix[i].length - 1, domain.length)) {
			return true;
		}
		i++;
	}
	// we would have exited if we'd found a good suffix, so return false
	return false;
}

function emailOK(emailAddr) {
	if (!(checkEmail(emailAddr))) {
		alert("The e-mail address you entered appears to be incorrect.\n" + "\n" + "Please verify the address format (example: jdoe@domain.com)")
	}
}