function validateComments() {
	
	if(document.getElementById("author").value == "") { 
		alert("Please enter your name."); 
		document.getElementById("author").focus();
		return false; 
	}
	
	if(document.getElementById("email").value == "") { 
		alert("Please enter your email address."); 
		document.getElementById("email").focus();
		return false; 
	}
	else {
		var result = echeck(document.getElementById("email").value);
		// validate email address
		if(result==false){
			document.getElementById("email").focus();
			return false;
		}
	}
	
	if(document.getElementById("comment").value == "") {
		alert("Please enter some comments.");
		document.getElementById("comment").focus();
		return false;
	}
	
	return true;
}

/**
 * DHTML email validation script. Courtesy of SmartWebby.com (http://www.smartwebby.com/dhtml/)
 */

function echeck(str) {
	var at="@";
	var dot=".";
	var lat=str.indexOf(at);
	var lstr=str.length;
	var ldot=str.indexOf(dot);
	if (str.indexOf(at)==-1){
		 alert("Please enter a valid email address.");
		 return false;
	}

	if (str.indexOf(at)==-1 || str.indexOf(at)==0 || str.indexOf(at)==lstr){
		 alert("Please enter a valid email address.");
		 return false;
	}

	if (str.indexOf(dot)==-1 || str.indexOf(dot)==0 || str.indexOf(dot)==lstr){
			alert("Please enter a valid email address.");
			return false;
	}

	 if (str.indexOf(at,(lat+1))!=-1){
			alert("Please enter a valid email address.");
			return false;
	 }

	 if (str.substring(lat-1,lat)==dot || str.substring(lat+1,lat+2)==dot){
			alert("Please enter a valid email address.");
			return false;
	 }

	 if (str.indexOf(dot,(lat+2))==-1){
			alert("Please enter a valid email address.");
			return false;
	 }
	
	 if (str.indexOf(" ")!=-1){
			alert("Please enter a valid email address.");
			return false;
	 }

	 return true;					
}