function chk_form(myForm) {
	
	var check = true;	// input is correct
	var errormessage = "";	// which input iss incorrect

	// Check name
	if(isblank(myForm.sendername.value)) {
		errormessage += "\n - Name ";
		check = false;
	}
	
	// Check if email is correct email format
	if(!chk_email(myForm.emailaddress.value)) {
		errormessage += "\n - Email ";
		check = false;
	}

		
	// Check message
	if(myForm.message.value.length == 0) {
		errormessage += "\n - Feedback message ";
		check = false;
	}

	// if any error, warn and stay in form
	if(check == false) {
		alert("Please verify the following fields: \n" + errormessage);
		return false;
	} else {
		return true;
	}
}


// is input blank
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;
} // end of isblank()}

// correct emailformat
function chk_email(emailStr) {
	var emailPat = /(^[\w-_à Ã&#128;áÃ?âÃ&#130;ãÃ&#131;äÃ&#132;Ã¥Ã&#133;æÃ&#134;çÃ&#135;èÃ&#136;éÃ&#137;êÃ&#138;ëÃ&#139;ìÃ&#140;íÃ?îÃ&#142;ïÃ?ðÃ?ñÃ&#145;òÃ&#146;óÃ&#147;ôÃ&#148;õÃ&#149;öÃ&#150;ùÃ&#153;úÃ&#154;ûÃ&#155;üÃ&#156;ýÃ?ÿÃ&#159;\.]*[\w-_à Ã&#128;áÃ?âÃ&#130;ãÃ&#131;äÃ&#132;Ã¥Ã&#133;æÃ&#134;çÃ&#135;èÃ&#136;éÃ&#137;êÃ&#138;ëÃ&#139;ìÃ&#140;íÃ?îÃ&#142;ïÃ?ðÃ?ñÃ&#145;òÃ&#146;óÃ&#147;ôÃ&#148;õÃ&#149;öÃ&#150;ùÃ&#153;úÃ&#154;ûÃ&#155;üÃ&#156;ýÃ?ÿÃ&#159;\.])@(\[\d{1,3}(\.\d{1,3}){3}]|[\w-_\.]*[\w-_\.]+)$/;
	var matchArray = emailStr.match(emailPat);
	if (matchArray == null) return false;
	// make sure the IP address domain is valid
	var IPArray = matchArray[2].match(/^\[(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})\]$/);
	if (IPArray != null){
		for (var i=1;i<=4;i++) {
			if (IPArray[i]>255)
				return false;
			}
 		}
	return true;
}


var newWin = null; 
function popUp(strURL, strType, strHeight, strWidth) { 
 var strOptions=""; 
 if (strType=="console") 
   strOptions="resizable,height="+ 
     strHeight+",width="+strWidth; 
 if (strType=="fixed") 
   strOptions="status,height="+ 
     strHeight+",width="+strWidth; 
 if (strType=="fixedscroll") 
   strOptions="status,scrollbars,height="+ 
     strHeight+",width="+strWidth; 
if (strType=="fixedpos") 
   strOptions="status,height,screenX=300,left=300,screenY=300,top=300,height="+ 
     strHeight+",width="+strWidth; 
 if (strType=="elastic") 
   strOptions="scrollbars,"+ 
     "resizable,height="+
     strHeight+",width="+strWidth; 
 if (strType=="elasticmenu") 
   strOptions="menubar,scrollbars,"+ 
     "resizable,height="+ 
     strHeight+",width="+strWidth; 
 newWin = window.open(strURL, 'newWin', strOptions); 
 newWin.focus();
 
}