using js with less elements

using js with less elements

Hi,
as i seen this page, i wanted to ask for help, today i've wanted to write a "randomize text code without the javascript display in the elements but i couldn't do it can someone tell me what i did wrong and correct me it? also this is an example i want to be same as this.  https://api.rtainc.co/twitch/8ball

and this is my code
  2. <html>
  3. <shadow><script type="text/javascript">
  4. var textarray = [
  5.  "Hi, $(user)",
  6.  "Welcome, $(user)",
  7.  "how r u $(user)",
  8.  "HYD $(user)"
  9. ];

  11. function RndText() {
  12.   var rannum= Math.floor(Math.random()*textarray.length);
  13.   document.getElementById('txt').innerHTML=textarray[rannum];
  14. }
  15. onload = function() { RndText(); }

  17. </script></shadow>

  19. <head></head>
  20. <body>
  21. <pre id="txt" style="word-wrap: break-word; white-space: pre-wrap;"></pre>
  22. </body>
  23. <style></style>
  24. </html>