Center a popup window on screen?

Question

How can we center a popup window opened via javascript window.open function on the center of screen variable to the currently selected screen resolution ?

Answer 1

You can use css to do it, just give the following properties to the element to be placed in the center of the popup

element{

position:fixed;
left: 50%;
top: 50%;
-ms-transform: translate(-50%,-50%);
-moz-transform:translate(-50%,-50%);
-webkit-transform: translate(-50%,-50%);
 transform: translate(-50%,-50%);

}

Answer 2

Facebook use the following algorithm to position their login popup window:

function PopupCenter(url, title, w, h) {
  var userAgent = navigator.userAgent,
      mobile = function() {
        return /\b(iPhone|iP[ao]d)/.test(userAgent) ||
          /\b(iP[ao]d)/.test(userAgent) ||
          /Android/i.test(userAgent) ||
          /Mobile/i.test(userAgent);
      },
      screenX = typeof window.screenX != 'undefined' ? window.screenX : window.screenLeft,
      screenY = typeof window.screenY != 'undefined' ? window.screenY : window.screenTop,
      outerWidth = typeof window.outerWidth != 'undefined' ? window.outerWidth : document.documentElement.clientWidth,
      outerHeight = typeof window.outerHeight != 'undefined' ? window.outerHeight : document.documentElement.clientHeight - 22,
      targetWidth = mobile() ? null : w,
      targetHeight = mobile() ? null : h,
      V = screenX < 0 ? window.screen.width + screenX : screenX,
      left = parseInt(V + (outerWidth - targetWidth) / 2, 10),
      right = parseInt(screenY + (outerHeight - targetHeight) / 2.5, 10),
      features = [];
  if (targetWidth !== null) {
    features.push('width=' + targetWidth);
  }
  if (targetHeight !== null) {
    features.push('height=' + targetHeight);
  }
  features.push('left=' + left);
  features.push('top=' + right);
  features.push('scrollbars=1');

  var newWindow = window.open(url, title, features.join(','));

  if (window.focus) {
    newWindow.focus();
  }

  return newWindow;
}

Answer 3

My version with ES6 JavaScript.
Works well on Chrome and Chromium with dual screen setup.

function openCenteredWindow({url, width, height}) {
    const pos = {
        x: (screen.width / 2) - (width / 2),
        y: (screen.height/2) - (height / 2)
    };

    const features = `width=${width} height=${height} left=${pos.x} top=${pos.y}`;

    return window.open(url, '_blank', features);
}

Example

openCenteredWindow({
    url: 'https://stackoverflow.com/', 
    width: 500, 
    height: 600
}).focus();

Answer 4

function fnPopUpWindow(pageId) {
     popupwindow("hellowWorld.php?id="+pageId, "printViewer", "500", "300");
}

function popupwindow(url, title, w, h) {
    var left = Math.round((screen.width/2)-(w/2));
    var top = Math.round((screen.height/2)-(h/2));
    return window.open(url, title, 'toolbar=no, location=no, directories=no, status=no, '
            + 'menubar=no, scrollbars=yes, resizable=no, copyhistory=no, width=' + w 
            + ', height=' + h + ', top=' + top + ', left=' + left);
}

<a href="javascript:void(0);" onclick="fnPopUpWindow('10');">Print Me</a>

Note: you have to use Math.round for getting the exact integer of width and height.

Answer 5

If you want to center it on the frame you are currently in, I would recommend this function:

function popupwindow(url, title, w, h) {
    var y = window.outerHeight / 2 + window.screenY - ( h / 2)
    var x = window.outerWidth / 2 + window.screenX - ( w / 2)
    return window.open(url, title, 'toolbar=no, location=no, directories=no, status=no, menubar=no, scrollbars=no, resizable=no, copyhistory=no, width=' + w + ', height=' + h + ', top=' + y + ', left=' + x);
} 

Similar to Crazy Tim's answer, but doesn't use window.top. This way, it will work even if the window is embedded in an iframe from a different domain.

Answer 6

It works very well in Firefox.
Just change the top variable to any other name and try again

        var w = 200;
        var h = 200;
        var left = Number((screen.width/2)-(w/2));
        var tops = Number((screen.height/2)-(h/2));

window.open("templates/sales/index.php?go=new_sale", '', 'toolbar=no, location=no, directories=no, status=no, menubar=no, scrollbars=no, resizable=no, copyhistory=no, width='+w+', height='+h+', top='+tops+', left='+left);