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

Here is an alternate version of the aforementioned solution...

const openPopupCenter = (url, title, w, h) => {
  const getSpecs = (w, h, top, left) => {
    return `scrollbars=yes, width=${w}, height=${h}, top=${top}, left=${left}`;
  };

  const getFirstNumber = (potentialNumbers) => {
    for(let i = 0; i < potentialNumbers.length; i++) {
      const value = potentialNumbers[i];

      if (typeof value === 'number') {
        return value;
      }
    }
  };

  // Fixes dual-screen position
  // Most browsers use window.screenLeft
  // Firefox uses screen.left
  const dualScreenLeft = getFirstNumber([window.screenLeft, screen.left]);
  const dualScreenTop = getFirstNumber([window.screenTop, screen.top]);
  const width = getFirstNumber([window.innerWidth, document.documentElement.clientWidth, screen.width]);
  const height = getFirstNumber([window.innerHeight, document.documentElement.clientHeight, screen.height]);
  const left = ((width / 2) - (w / 2)) + dualScreenLeft;
  const top = ((height / 2) - (h / 2)) + dualScreenTop;
  const newWindow = window.open(url, title, getSpecs(w, h, top, left));

  // Puts focus on the newWindow
  if (window.focus) {
    newWindow.focus();
  }

  return newWindow;
}