Create YT Link from URLs List

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Create YT Playlist Link from URLs List</title>
<script type="text/javascript">
  function replaceFunction() {
    var output = document.getElementById("urlList").value;
    if (output != "") {
      output = output.replaceAll("https://www.youtube.com/watch?v=", "");   // isolate ID strings
      output = output.replace(/\s+/g, ",");   // substitute space(s) for comma
      output = document.querySelector('input[name="URLtype"]:checked').value + output;
      document.getElementById("output").innerHTML = output;
    }
  }
</script>
<script type="text/javascript">
  function resetFunction() {
    document.getElementById("urlList").value=null;
    document.getElementById("output").innerHTML=null;
    document.getElementById("Mobile").checked = true;
  }
</script>
</head>

<body>
<h2>Create YT Playlist Link from URLs List</h2>
<textarea rows='7' cols='50' id='urlList'></textarea><br><br>
Select a YouTube device:<br>
<input type="radio" id="Mobile" name="URLtype" value="https://m.youtube.com/watch_videos?video_ids=" checked>Mobile: https://m.youtube.com/watch_videos?video_ids=</input><br>
<input type="radio" id="PC" name="URLtype" value="https://www.youtube.com/watch_videos?video_ids=">PC: https://www.youtube.com/watch_videos?video_ids=</input><br><br>
<input type='button' value='Create' onclick='replaceFunction()'/>&nbsp;&nbsp;<input type="button" value="Reset" onClick='resetFunction()'/>
<br><br>
<div id="output"></div>

</body>
</html>