change element by id color 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: javascript change color

var span = document.getElementsByTagName("span")[0];
span.style.color = "red";