How to center align pop up div using Javascript

How to align a pop up division to center of monitor/screen using javascript?

I tried using screen.width and screen.height to get center. But the 开发者_JAVA技巧division gets aligned to center of scrolling page vertically

Thanks in advance for any help and suggestions

Try this:

<div id="popup" class="popup">
  This a vertically and horizontally centered popup.
</div>

<a onclick="showPopup('popup');">Show Popup</a>

<style type="text/css">
  .popup {
    width:200px;
    height:100px;
    position:absolute;
    top:50%;
    left:50%;
    margin:-50px 0 0 -100px; /* [-(height/2)px 0 0 -(width/2)px] */
    display:none;
  }
</style>

<script type="text/javascript">
  function showPopup(id) {
    var popup = document.getElementById(id);
    popup.style.display = 'block';
  }
</script>

CSS explained: The div is 200x100, you position it 50% from the top and 50% from the left, but to have it centered fully, you need to substract from that 50% values the half of the width and height, the way to do this is to use negative margins, hence margin-top should be the negative value of the height/2 and margin-left should be the negative value of the width/2.

How about just doing with CSS:

<div class="div">Some Content......</div>

.div {
   margin-left: auto;
   margin-right: auto;
}

try:

 function msgBox(message)
 {
  var msgbox = document.getElementById("msgbox");
  msgbox.innerHTML = message;
  var x = (window.innerWidth / 2) - (msgbox.offsetWidth / 2);
  var y = (window.offsetHeight / 2) - (msgbox.offsetHeight / 2);              
  msgbox.style.top = y;
  msgbox.style.left = x;
  msgbox.style.display = "block";
 }

Try fixed-positioning:

#box {
  position: fixed;
  width: 40%;
  margin: 200px 30%;
}

It's only horizontally centered. Vertical will take some playing with. I have no idea how browsers act differently with the vertical alignment.

I also had this vertical centering problem on any webpage that required scrolling.

Switching to position: fixed solved it, so:

position:fixed;
top:50%;
left:50%;
margin:-50px 0 0 -100px; /* [-(height/2)px 0 0 -(width/2)px] */

This worked in firefox, google chrome, safari (pc) and IE9.

Unfortunately, I wanted it to appear in front of an pdf file - the pop up did appear in front using Firefox, Chrome but went behind in IE9 and Safari....