CODE EXAMPLE FOR HTML

html copy button

HTML:
<!-- The text field -->
<input type="text" value="Hello World" id="myInput">

<!-- The button used to copy the text -->
<button onclick="myFunction()">Copy text</button>

JAVASCRIPT:
function myFunction() {
  /* Get the text field */
  var copyText = document.getElementById("myInput");

  /* Select the text field */
  copyText.select();
  copyText.setSelectionRange(0, 99999); /* For mobile devices */

   /* Copy the text inside the text field */
  navigator.clipboard.writeText(copyText.value);

  /* Alert the copied text */
  alert("Copied the text: " + copyText.value);
}