Open popup window in center of screen in javascript

gistfile1.js

var top = window.screen.height - 300;
    top = top > 0 ? top/2 : 0;
            
var left = window.screen.width - 400;
    left = left > 0 ? left/2 : 0;

var uploadWin = window.open(url,"Upload Chapter content","width=400,height=300" + ",top=" + top + ",left=" + left);
    uploadWin.moveTo(left, top);
    uploadWin.focus();

This can be used also to center popup window in center of screen in javascript
var width = 600;
var height = 600;
var left = (screen.width - width) / 2;
var top = (screen.height - height) / 2;
var popup = window.open(pdfUrl, "_blank", "width=" + width + ",height=" + height + ",left=" + left + ",top=" + top);