Help with adding a window alert to this script

[Chrisj]

The web cam recorder script that I'm working with has the "navigator', etc. code and the end of the script as shown below.

 

I tried to add this code, so people trying to use the webcam recorder in IE will see an alert dialog box(without success):

 

		    if (!navigator || !navigator.getUserMedia || !navigator.mediaDevices.getUserMedia) {
		           if (window.confirm('Your browser does not support WebVideo, try Google/Chrome'))
		    	   {
		    window.location.href='https://../index.php';
		    		} else {
		    		    show();
}
}

Maybe I've got something wrong. The window.confirm message still doesn't display in IE. Here's the script without the 'alert' code:

                <script>
		             const video = document.querySelector('video')
		             const startvideo = document.querySelector('.start')
		             const stopvideo = document.querySelector('.stop')
		             const upload = document.querySelector('.upload')
		             const initRecorder = stream => {
		             const recorder = new MediaRecorder(stream)
		             let blob
		               video.srcObject = stream
		               startvideo.removeAttribute('disabled')
		               video.addEventListener('loadedmetadata', () => {
		               video.play()
		               })
		               recorder.addEventListener('dataavailable', ({ data }) => {
		               video.srcObject = null
		               video.src = URL.createObjectURL(data)
		               // Create a blob from the data for upload
		               blob = new Blob([data], { type: 'video/webm' })
		               })
		 
		               startvideo.addEventListener('click', () => {
		               stopvideo.removeAttribute('disabled')
		               show()
		               reset()
		               start()
		               recorder.start()
		 
		 etc., etc, ............................
		 
		               navigator
		                 .mediaDevices
		                 .getUserMedia({ video: true })
		                 .then(initRecorder)
		                 .catch(console.error)
		 
         </script>

Any suggestions/enlightenment to get the 'alert'/confirm code to work with this script, will be appreciated.