Check out example codes for "jquery in html". It will help you in understanding the concepts better.

Code Example 1

<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.0/jquery.min.js"></script>

Code Example 2

<head>

<script src="https://ajax.aspnetcdn.com/ajax/jQuery/jquery-3.4.1.min.js"></script>

</head>

Code Example 3

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>

Code Example 4

var itemtoReplaceContentOf = $('#regTitle');
itemtoReplaceContentOf.html('');
newcontent.appendTo(itemtoReplaceContentOf);

Code Example 5

<script
  src="https://code.jquery.com/jquery-3.4.1.js"
  integrity="sha256-WpOohJOqMqqyKL9FccASB9O0KwACQJpFTUBLTYOVvVU="
  crossorigin="anonymous"
></script>

Code Example 6

<head>

<!-- Include meta tag to ensure proper rendering and touch 
	zooming -->
<meta name="viewport" content="width=device-width, 
	initial-scale=1">

<!-- Include jQuery Mobile stylesheets -->

	<link rel="stylesheet" href="http://code.jquery.com/mobile/1.4.5/jquery.mobile-1.4.5.min.css">

	
<!-- Include the jQuery library -->

	<script src="http://code.jquery.com/jquery-1.11.3.min.js"></script>

	
<!-- Include the jQuery Mobile library -->

	<script src="http://code.jquery.com/mobile/1.4.5/jquery.mobile-1.4.5.min.js"></script>


</head>

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