var fbNameDef="Name (required)";
var fbEmailDef="Email (required)";
var fbFeedbackDef="Your feedback (required)";
var fbQuestionDef="Got a good Quizz question? (optional)\nWe are collecting interesting Hong Kong facts for future Quizztory editions. If you know of any, please share there with us. Thanks !"




function defOnClick(v, def){
	return v==def ? '' : v;
}

function defOnBlur(v, def){
	return v==""  ? def : v;
}


function defQuestionOnClick(v){
	if( v.replace(/\n|\r\n/g, '') == fbQuestionDef.replace(/\n|\r\n/g, '') )
		$("#your_question").val("");
	else
		$("#your_question").val(v);
}

function defQuestionOnBlur(v){
	if( v == '' )
		$("#your_question").val(fbQuestionDef);
	else
		$("#your_question").val(v);
}


function submitFeedbackForm(){
	var errorMsg = "";
	if ($("#your_name").val()=='' || $("#your_name").val()==fbNameDef)
		errorMsg += "Please input your name.\n";
	if ($("#your_email").val()=='' || $("#your_email").val()==fbEmailDef)
		errorMsg += "Please input your email address.\n";
	if ( !validateEmail( $("#your_email").val() ) )
		errorMsg += "Please input a valid email address.\n";
	if ($("#your_feedback").val()=='' || $("#your_feedback").val()==fbFeedbackDef)
		errorMsg += "Please input your feedback.\n";

	if (errorMsg==""){

		document.getElementById('feedback_form').submit();
	}else{
		alert(errorMsg);
	}
		
}


function validateEmail(v){ 
	var emailPattern = /^[a-zA-Z0-9._-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,4}$/; 
	return emailPattern.test(v); 
}
function showAllThumb(){
	var arr=['chess','board','question1','question2','question3','question4'];
	for(i=0; i<arr.length; i++)
		document.getElementById(arr[i]).style.display='block';
}

function swapProductImg(img, ele){
	document.getElementById('img_detail').src='images/'+img;
}