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Java Script Hello World

The following script will display 'Hello World' both in a popup window and in the browser's console. To execute the script, it must be run within a web browser.

You can view the console output by accessing the browser's developer tools.

hello-world-js.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Hello World!</title>
</head>
<body>
    <h1>Hello World! from JS in a script tag</h1>
    <script>
        alert('Hello world!');
        const h1 = document.querySelector('h1');
        console.log(h1.textContent);
    </script>
</body>
</html>

In modern HTML (specifically, HTML5), it's no longer necessary to specify the type attribute when using JavaScript within a <script> tag. Browsers that support HTML5 will default to JavaScript if the type attribute is omitted.

In previous versions of HTML, it was common to see the type attribute set like this:

<script type="text/javascript">
  // Your JavaScript code here
</script>

However, since HTML5, this is considered unnecessary, and the following is completely acceptable and standard:

<script>
  // Your JavaScript code here
</script>

If you're writing HTML that must conform to older standards or you want to be explicitly clear about the type, you can still include the type attribute. However, for most modern web development, it can safely be omitted.