how to alter css using javascript code example

Example 1: how to change the color using js

<!DOCTYPE html>
<html>
<head>
<script>
function display()
{
var col=document.getElementById("demo");
col.style.color="#FF0000";
}
</script>
</head>
<body>

<h1>My First JavaScript</h1>
<p id="demo">click on the button below.....</p>

<button onclick="display()">Display</button>

</body>
</html>

Example 2: how to change style of an element using javascript

<html>
<body>

<p id="p2">Hello World!</p>

<script>
document.getElementById("p2").style.color = "blue";
</script>

<p>The paragraph above was changed by a script.</p>

</body>
</html>