새 창을 열지 않고 Popup 보여주기

원본: http://www.pat-burt.com/web-development/how-to-do-a-css-popup-without-opening-a-new-window/

아래 그림처럼 새창을 열지않고, CSS 와 JavaScript 만을 이용하여 Popup 을 보여주는 방법이다.

CSS 

#blanket {
background-color:#111;
opacity: 0.65;
filter:alpha(opacity=65);
position:absolute;
z-index: 9001;
top:0px;
left:0px;
width:100%;
}
#popUpDiv {
position:absolute;
background-color:#eeeeee;
width:300px;
height:300px;
z-index: 9002;

JavaScript

function toggle(div_id) {
	var el = document.getElementById(div_id);
	if ( el.style.display == 'none' ) {	el.style.display = 'block';}
	else {el.style.display = 'none';}
}
function blanket_size(popUpDivVar) {
	if (typeof window.innerWidth != 'undefined') {
		viewportheight = window.innerHeight;
	} else {
		viewportheight = document.documentElement.clientHeight;
	}
	if ((viewportheight > document.body.parentNode.scrollHeight) && (viewportheight > document.body.parentNode.clientHeight)) {
		blanket_height = viewportheight;
	} else {
		if (document.body.parentNode.clientHeight > document.body.parentNode.scrollHeight) {
			blanket_height = document.body.parentNode.clientHeight;
		} else {
			blanket_height = document.body.parentNode.scrollHeight;
		}
	}
	var blanket = document.getElementById('blanket');
	blanket.style.height = blanket_height + 'px';
	var popUpDiv = document.getElementById(popUpDivVar);
	popUpDiv_height=blanket_height/2-150;//150 is half popup's height
	popUpDiv.style.top = popUpDiv_height + 'px';
}
function window_pos(popUpDivVar) {
	if (typeof window.innerWidth != 'undefined') {
		viewportwidth = window.innerHeight;
	} else {
		viewportwidth = document.documentElement.clientHeight;
	}
	if ((viewportwidth > document.body.parentNode.scrollWidth) && (viewportwidth > document.body.parentNode.clientWidth)) {
		window_width = viewportwidth;
	} else {
		if (document.body.parentNode.clientWidth > document.body.parentNode.scrollWidth) {
			window_width = document.body.parentNode.clientWidth;
		} else {
			window_width = document.body.parentNode.scrollWidth;
		}
	}
	var popUpDiv = document.getElementById(popUpDivVar);
	window_width=window_width/2-150;//150 is half popup's width
	popUpDiv.style.left = window_width + 'px';
}
function popup(windowname) {
	blanket_size(windowname);
	window_pos(windowname);
	toggle('blanket');
	toggle(windowname);		
}

csspopup.js

csspopup.html