Add script files in WordPress ERROR !!!

My codes are

01. <script type="text/javascript" src="<?=get_template_directory_uri();?>https://s3-us-west-2.amazonaws.com/s.cdpn.io/499416/demo.js"></script>

02. <script type="text/javascript" src="https://s3-us-west-2.amazonaws.com/s.cdpn.io/499416/demo.js"></script>


Both codes didn't work. Can anyone give a better suggestion to add the script files in WordPress?