javascript input text value 클립보드 복사

function copy_to_clipboard() {
  var copyText = document.getElementById('myInput');
  copyText.select();
  copyText.setSelectionRange(0, 99999);
  document.execCommand('Copy');
  alert('복사되었습니다, 감사합니다.');
}

              <div class="url_copy">
                <input type="text" id="myInput" value="<?='http://' . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];?>" readonly>
                <button type="button" class="btn_copy" onclick="copy_to_clipboard()">url복사</button>
              </div>