The <script> Tag
In HTML, JavaScript code is inserted between <script> and </script> tags.
<script>
document.getElementById("demo").innerHTML = "My First JavaScript";
</script>JavaScript Functions and Events
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.
JavaScript in <head> or <body>
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.
JavaScript in <head>
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>
<h2>Demo JavaScript in Head</h2>
<p id="demo">A Paragraph</p>
<button type="button" onclick="myFunction()">Try it</button>
</body>
</html>
JavaScript in <body>
In this example, a JavaScript function is placed in the <body> section of an HTML page.
The function is invoked (called) when a button is clicked:
External JavaScript
Scripts can also be placed in external files: