Is it possible to control the camera light on a phone via a website?

Question

Is it possible to control the camera's flashlight on a phone via a website? Say through Chrome or Firefox. I know it's possible using an Android or iOS app, which is implemented by all the flashlight apps out there. And I know one can control the cameras via the getUserMedia family of functions. If not, does anyone know when will it become available?

Answer 1

Here is a little "torch-app" for a website:

Edit 1: I also made a jsfiddle

//Test browser support
const SUPPORTS_MEDIA_DEVICES = 'mediaDevices' in navigator;

if (SUPPORTS_MEDIA_DEVICES) {
  //Get the environment camera (usually the second one)
  navigator.mediaDevices.enumerateDevices().then(devices => {
  
    const cameras = devices.filter((device) => device.kind === 'videoinput');

    if (cameras.length === 0) {
      throw 'No camera found on this device.';
    }
    const camera = cameras[cameras.length - 1];

    // Create stream and get video track
    navigator.mediaDevices.getUserMedia({
      video: {
        deviceId: camera.deviceId,
        facingMode: ['user', 'environment'],
        height: {ideal: 1080},
        width: {ideal: 1920}
      }
    }).then(stream => {
      const track = stream.getVideoTracks()[0];

      //Create image capture object and get camera capabilities
      const imageCapture = new ImageCapture(track)
      const photoCapabilities = imageCapture.getPhotoCapabilities().then(() => {

        //todo: check if camera has a torch

        //let there be light!
        const btn = document.querySelector('.switch');
        btn.addEventListener('click', function(){
          track.applyConstraints({
            advanced: [{torch: true}]
          });
        });
      });
    });
  });
  
  //The light will be on as long the track exists
  
  
}

<button class="switch">On / Off</button>

The code is heavily inspired by this repository, this webseries and this blog-post

Edit 2: This does only works in Chrome (and maybe Opera). It does not work in Chrome on iOS, because Chrome cannot access the camera. I cannot test it on android for now. I created a new jsfiddle, with an output. If you have an android phone and it does not work for you, it will maybe tell why: https://jsfiddle.net/jpa1vwed/

Feel free to debug, comment and edit.