introduction.html

<!DOCTYPE html>
<html>
<head>
	<title>Introduction</title>
</head>
<body>

	<h3 id="heading3">Hello Javascript</h3>

	<button onclick='document.getElementById("heading3").style.fontSize="20px"'> Change Font 20px</button>
	<button onclick="document.getElementById('heading3').style.fontSize='50px'">Change font 50px</button>

	<button onclick="document.getElementById('heading3').style.display='block'">Show Heading</button>
	<button onclick="document.getElementById('heading3').style.display='none'">Hide Heading</button>


	<br/><hr/>

	<div id="container">Hello World</div>

	<button onclick='document.getElementById("container").innerHTML = "Learning Javascript"'>Change Text</button>

	<br/><hr/>


	<img id="thumbnail" src="https://picsum.photos/300/300?image=1084">

	<button onclick="document.getElementById('thumbnail').src='https://picsum.photos/300/300?image=1080'">Change Image</button>

	<br/><hr/>

</body>
</html>