how to click and copy in html button using javascript

document.execCommand("copy");

  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 */
  document.execCommand("copy");

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