Email Validation (w/o regexp)

talk open source
1

I’m needing an email validation algorithm that works without regexp (for use with flash versions < 8, etc…) and I came across a script that I adapted a little.

Here is the script in JavaScript. Mainly what I’m looking for is people to tell me if there are any important rules that I have missed out.

Thank you:

/**
 * DHTML email validation script. Courtesy of SmartWebby.com (http://www.smartwebby.com/dhtml/)
 * Edits, Additions and Reformatting (inc. comments) by Paul Scott (http://www.icio.co.uk/)
 */

function echeck(str) {

	// Vars
	var at="@";
	var dot=".";
	var badmail=false;

	var lat=str.indexOf(at);
	var lstr=str.length;
	var ldot=str.indexOf(dot);

	var chars = "+-._0123456789abcdefghijklmnopqrstuvwyxzABCDEFGHIJKLMNOPQRSTUVWXYZ";

	// TEST CHARACTERS
	// ******************************
	var i;
	for (i=0; i<lstr; i++) {
		if (chars.indexOf(lstr.charAt(i))==-1) {
			badmail = true;
			break;
		}
	}

	// OTHER TESTS
	// ******************************
	// Test for an @, test that @ is not the first character, test @ is not the last character
	if (str.indexOf(at)==-1 || str.indexOf(at)==0 || str.indexOf(at)==lstr)
		badmail = true;

	// Test for a ., test that . is not the first character, that . is not the last character
	if (str.indexOf(dot)==-1 || str.indexOf(dot)==0 || str.indexOf(dot)==lstr)
		badmail = true;

	// Test that there is only one @
	if (str.indexOf(at,(lat+1))!=-1)
		badmail = true;

	// Test that there is not a . before the @, test that there is not a . after the @
	if (str.substring(lat-1,lat)==dot || str.substring(lat+1,lat+2)==dot)
		badmail = true;

	// Test that there is a . after the @ and that there is a at least 2 characters in between
	if (str.indexOf(dot,(lat+3))==-1)
		badmail = true;

	// Test that there are no spaces
	if (str.indexOf(" ")!=-1)
		badmail = true;

	// Test that there is a domain extension of >= 2 characters
	if (lstr-str.lastIndexOf(dot)>3)
		badmail = true;


	return !badmail;
}