HTML Script - 2 Tags and its Attributes (Reference)

<script>

Defines a client-side executable code. By Default, Html parse until js file, then download and execute and resume. By Using Async attribute, Html parse and continue to download js files ,and stop only while js execution By using Defer attribute, Html parse and continue to download js files and finish parsing and then start js execution

<script src="URL_to_js_file"></script>

<script>
  // Javascript code
</script>


<!-- Attributes - async, charset, defer, src, type, crossorigin, integrity, nonce. -->

<noscript>

Defines an alternate content if browser does not support client-side scripts.

<script>
  // Javascript code
</script>
<noscript>Your browser does not support JavaScript!</noscript>