function validate(f) {
	if((f.name.value == null) || (f.name.value == "") || isblank(f.name.value)){
		alert("You must give a name");
		f.name.focus();
		return false;
	};
	
	// check to see if the email's valid
	if (!validEmail(f.email.value)) {
		alert("Invalid email address");
		f.email.focus();
		f.email.select();
		return false;
	};
	
	// make sure user choose a rate
	rateOption = -1;
	for (i=0; i<f.rate.length; i++) {
		if (f.rate[i].checked) {
			rateOption = i;
		};
	};
	if (rateOption == -1) {
		alert("You must choose a rate");
		return false;
	};
	 
	// If we made it to here, everything's valid, so return true
        return true;
    
}
 

function validEmail(email) {
	invalidChars = " /:,;";
	
	if (email == "") {						// cannot be empty
		return false;
	};

	for (i=0; i<invalidChars.length; i++) {	// does it contain any invalid characters?
		badChar = invalidChars.charAt(i);
		if (email.indexOf(badChar,0) > -1) {
			return false;
		};
	};

	atPos = email.indexOf("@",1);			// there must be one "@" symbol

	if (atPos == -1) {
		return false;
	};

	if (email.indexOf("@",atPos+1) != -1) {	// and only one "@" symbol
		return false;
	};

	periodPos = email.indexOf(".",atPos);

	if (periodPos == -1) {					// and at least one "." after the "@"
		return false;
	};

	if (periodPos+3 > email.length)	{		// must be at least 2 characters after the "."
		return false;
	};

	return true;
}

// utility function that returns true if a string contains only 
// whitespace chars
function isblank(s){

	for(var i = 0; i < s.length; i++){

		var c = s.charAt(i);
		if((c != ' ') && (c != '\n') && (c != '\t'))
			return false;
	};

	return true;
}