1.0.0 • Public • Published

getScreenId | Capture Screen on Any Domain!

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  1. Install this: https://chrome.google.com/webstore/detail/screen-capturing/ajhifddimkapgcifgcodmmfdlknahffk
  2. Now use below codes on any HTTPs domain.
  3. Remember, HTTPs is required.
  4. getScreenId gives you "MediaStream" object; you can share that object with other users using AppRTC demo, SimpleWebRTC or EasyRTC or PeerJs libraries, or any standalone peer-to-peer demo.
  5. In simple words, you have to use RTCPeerConnection API along with getScreenId to share screen with other users.
npm instll @muaz-khan/getscreenid

Hacking to use single chrome-extension on any domain!

* This script is a hack used to support single chrome extension usage on any domain.

* This script has issues, though.
* It uses "postMessage" mechanism which fails to work if someone is using it from inside an <iframe>.
* The only solution for such cases is, use WebSockets or external servers to pass "source-ids".

You don't need to PUBLISH/deploy your own chrome-extension when using this script!

LocalHost server

node server.js

Nope open: https://localhost:9001/

How to use?

<script src="https://cdn.WebRTC-Experiment.com/getScreenId.js"></script>
<script src="https://webrtc.github.io/adapter/adapter-latest.js"></script>

<video controls autoplay playsinline></video>


This method allows you get chrome-media-source-id; which can be used to capture screens.

getScreenId(function (error, sourceId, screen_constraints) {
    // error    == null || 'permission-denied' || 'not-installed' || 'installed-disabled' || 'not-chrome'
    // sourceId == null || 'string' || 'firefox'

    if(navigator.userAgent.indexOf('Edge') !== -1 && (!!navigator.msSaveOrOpenBlob || !!navigator.msSaveBlob)) {
        navigator.getDisplayMedia(screen_constraints).then(stream => {
            document.querySelector('video').srcObject = stream;
        }, error => {
            alert('Please make sure to use Edge 17 or higher.');

    if(error == 'not-installed') {
      alert('Please install Chrome extension.');

    navigator.mediaDevices.getUserMedia(screen_constraints).then(function (stream) {
        document.querySelector('video').srcObject = stream;

        // share this "MediaStream" object using RTCPeerConnection API
    }).catch(function (error) {
      console.error('getScreenId error', error);

      alert('Failed to capture your screen. Please check Chrome console logs for further information.');


getScreenId(function (error, sourceId, screen_constraints) {
    // error    == null || 'permission-denied' || 'not-installed' || 'installed-disabled' || 'not-chrome'
    // sourceId == null || 'string' || 'firefox'

    if(sourceId && sourceId != 'firefox') {
        screen_constraints = {
            video: {
                mandatory: {
                    chromeMediaSource: 'screen',
                    maxWidth: 1920,
                    maxHeight: 1080,
                    minAspectRatio: 1.77

        if (error === 'permission-denied') return alert('Permission is denied.');
        if (error === 'not-chrome') return alert('Please use chrome.');

        if (!error && sourceId) {
            screen_constraints.video.mandatory.chromeMediaSource = 'desktop';
            screen_constraints.video.mandatory.chromeMediaSourceId = sourceId;

    navigator.getUserMedia = navigator.mozGetUserMedia || navigator.webkitGetUserMedia;
    navigator.getUserMedia(screen_constraints, function (stream) {
        document.querySelector('video').src = URL.createObjectURL(stream);

        // share this "MediaStream" object using RTCPeerConnection API
    }, function (error) {
      console.error('getScreenId error', error);

      alert('Failed to capture your screen. Please check Chrome console logs for further information.');


This method allows you detect whether chrome extension is installed or not:

getChromeExtensionStatus(function(status) {
    if (status === 'installed-enabled') alert('installed');
    if (status === 'installed-disabled') alert('installed but disabled');
    // etc.

How it works?

  • Your script will make a postMessage request to getScreenId.js
  • getScreenId.js will connect with chrome-extension using an internal <iframe>.
  • That <iframe> is loaded from domain: https://www.webrtc-experiment.com/
  • That <iframe> can connect with chrome-extension. It can send/receive postMessage data.
  • Same postMessage API are used to pass screen-id back to your script.

Custom Parameter

Pass second argument to getScrenId method:

  • true means that capture system audio i.e. speakers
  • [] array means that capture custom array items
getScreenId(successCallback, true);    // capture speakers
getScreenId(successCallback, ['tab']); // capature only tab
getScreenId(successCallback, ['window']); // capature only app's windows
getScreenId(successCallback, ['screen', 'audio']); // capature only screen with speakers


Deploy extension yourself?



getScreenId.js is released under MIT licence . Copyright (c) Muaz Khan.

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