I'm trying to build a web app using Ionic2 and cordova ,for an augmented reality purpose. This code work but only the front camera work ! how can i activate the back camera ?
video = document.querySelector('video');
  canvas = document.querySelector('canvas');
  context = canvas.getContext("2d");
  //Canvas prendre les dimensions de la fenétre 
  //qu'il le contien
  canvas.width = parseInt(window.innerWidth);
  canvas.height = parseInt(window.innerHeight);
  function hasGetUserMedia() {
    return !!(navigator.getUserMedia || navigator.webkitGetUserMedia ||
              navigator.mozGetUserMedia || navigator.msGetUserMedia);
  }
  if (hasGetUserMedia()) {
    function successCallback(stream){
      if (window.webkitURL) {
        video.src = window.webkitURL.createObjectURL(stream);
      } else if (video.mozSrcObject !== undefined) {
        video.mozSrcObject = stream;
      } else {
        video.src = stream;
      }
    }
    function errorCallback(error){
      //Rien a faire
    }
    //Qualité de la video HD(1280x720)
    navigator.getUserMedia({ video: { facingMode: { exact: "environment" } } },
                            successCallback,
                            errorCallback
                          );
    } else {
      alert('getUserMedia() is not supported in your device');
    }
}