In HTML, JavaScript code must be inserted between <script>
and </script>
tags.
<script>
document.getElementById("demo").innerHTML = "My First JavaScript";
</script>
Old JavaScript examples may use a type attribute: <script type="text/javascript">.
The type attribute is not required. JavaScript is the default scripting language in HTML.
A JavaScript function
is a block of JavaScript code, that can be executed when "called" for.
For example, a function can be called when an event occurs, like when the user clicks a button.
You will learn much more about functions and events in later chapters.
You can place any number of scripts in an HTML document.
Scripts can be placed in the <body>
, or in the <head>
section of an HTML page, or in both.
In this example, a JavaScript function
is placed in the <head>
section of an HTML page.
The function is invoked (called) when a button is clicked:
<!DOCTYPE html>
<html>
<head>
<script>
function myFunction() {
document.getElementById("demo").innerHTML = "Paragraph changed.";
}
</script>
</head>
<body>
<h1>A Web Page</h1>
<p id="demo">A Paragraph</p>
<button type="button" onclick="myFunction()">Try it</button>
</body>
</html>