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

Question

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