สอบถามเรื่องการทำ Background เป็นแบบ fadeIn,fadeOut

//0 means disabled; 1 means enabled;
var popupStatus = 0;

function loadPopup(){
	if(popupStatus==0){
		$("#backgroundPopup").css({
			"opacity": "0.7"
		});
		$("#backgroundPopup").fadeIn("slow");
		$("#popupContact").fadeIn("slow");
		popupStatus = 1;
	}
}

function disablePopup(){
	if(popupStatus==1){
		$("#backgroundPopup").fadeOut("slow");
		$("#popupContact").fadeOut("slow");
		popupStatus = 0;
	}
}

function centerPopup(){
	var windowWidth = document.documentElement.clientWidth;
	var windowHeight = document.documentElement.clientHeight;
	var popupHeight = $("#popupContact").height();
	var popupWidth = $("#popupContact").width();
	$("#popupContact").css({
		"position": "absolute",
		"top": windowHeight/2-popupHeight/2,
		"left": windowWidth/2-popupWidth/2
	});
	
	$("#backgroundPopup").css({
		"height": windowHeight
	});
	
}

$(document).ready(function(){
	$("#button").click(function(){
		centerPopup();
		loadPopup();
	});

	$("#popupContactClose").click(function(){
		disablePopup();
	});

	$("#button_Action").click(function(){
		disablePopup();
	});

	$(document).keypress(function(e){
		if(e.keyCode==27 && popupStatus==1){
			disablePopup();
		}
	});

});