var isMobile = /iPhone|iPad|iPod|Android/i.test(navigator.userAgent); if (isMobile) {

 Webcam.set({
        width: 250,
        height: 200,
        image_format: 'jpg',
        jpeg_quality: 90,
        dest_width: 150,
        dest_height: 150, 
         constraints: {

facingMode: 'environment' }
});

  }