HTML

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <link
      rel="icon"
      href="data:image/svg+xml,<svg xmlns=%22http://www.w3.org/2000/svg%22 viewBox=%220 0 100 100%22><text y=%22.9em%22 font-size=%2290%22>🎉</text></svg>"
    />
    <title>How to use multiple screens</title>
    <link rel="stylesheet" href="/style.css" />
    <!-- TODO: Devsite - Removed inline handlers -->
    <!-- <script src="/script.js" type="module"></script> -->
  </head>
  <body>
    <h1>How to use multiple screens</h1>
    <div>
      <div>
        Permission Status:
        <span id="permissionStatus"></span>
      </div>
      <div>Screens Available: <span id="screensAvail"></span></div>
    </div>
    <button id="detectScreen">Detect Screens</button>
    <button id="create" disabled>Create Page On Random Screen</button>
  </body>
</html>

CSS


        :root {
  color-scheme: dark light;
}

html {
  box-sizing: border-box;
}

*,
*:before,
*:after {
  box-sizing: inherit;
}

body {
  margin: 1rem;
  font-family: system-ui, sans-serif;
}

JS


        const detectButton = document.querySelector('#detectScreen');
const createButton = document.querySelector('#create');
const permissionLabel = document.querySelector('#permissionStatus');
const screensAvailLabel = document.querySelector('#screensAvail');
const popupUrl = 'supporting-popup.html';
let screenDetails = undefined;
let permission = undefined;
let currentScreenLength = undefined;

detectButton.addEventListener('click', async () => {
  if ('getScreenDetails' in window) {
    screenDetails = await window.getScreenDetails();
    screenDetails.addEventListener('screenschange', (event) => {
      if (screenDetails.screens.length !== currentScreenLength) {
        currentScreenLength = screenDetails.screens.length;
        updateScreenInfo();
      }
    });
    try {
      permission =
        (await navigator.permissions.query({ name: 'window-placement' }))
          .state === 'granted'
          ? 'Granted'
          : 'No Permission';
    } catch (err) {
      console.error(err);
    }
    currentScreenLength = screenDetails.screens.length;
    updateScreenInfo();
  } else {
    screenDetails = window.screen;
    permission = 'Multi-Screen Window Placement API - NOT SUPPORTED';
    currentScreenLength = 1;
    updateScreenInfo();
  }
});

createButton.addEventListener('click', () => {
  const screen =
    screenDetails.screens[Math.floor(Math.random() * currentScreenLength)];
  const options = {
    x: screen.availLeft,
    y: screen.availTop,
    width: screen.availWidth,
    height: screen.availHeight,
  };
  window.open(popupUrl, '_blank', getFeaturesFromOptions(options));
});

const getFeaturesFromOptions = (options) => {
  return (
    'left=' +
    options.x +
    ',top=' +
    options.y +
    ',width=' +
    options.width +
    ',height=' +
    options.height
  );
};

const updateScreenInfo = () => {
  screensAvailLabel.innerHTML = currentScreenLength;
  permissionLabel.innerHTML = permission;
  if ('getScreenDetails' in window && screenDetails.screens.length > 1) {
    createButton.disabled = false;
  } else {
    createButton.disabled = true;
  }
};