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JavaScript Basic Program

This basic javascript program is used to output a “Hello World!!” message in the browser. Javascript code must be inserted inside <script> tag within the HTML file.

<html>
<head>
    <title>JavaScript Basic Program</title>
</head>

<body>
    // Writes text directly into the web page
    <script language="javascript" style="text/javascript">
        document.write("Hello World!!");
    </script>
</body>

</html>

In the next tutorial, we will share how to run these programs in your computer. For now, you can run above HTML code directly via online editor such as http://codepen.io/pen/

Using alert(), console.log(), and document.write()

Here’s a another HTML program that use different JavaScript methods—alert(), console.log(), and document.write() to print some message at different places.

<!DOCTYPE html>
<html>
<head>
  <title>JavaScript Basics Example</title>
  <script>
    // Shows a popup alert box when the page loads
    alert("Welcome to JavaScript!");

    // Prints a message in the browser's console (press F12 to see it)
    console.log("This runs from the head.");
  </script>
</head>
<body>
  <h1>JavaScript Output Example</h1>

  <script>
    // Writes text directly into the web page
    document.write("Hello World!!");
  </script>
</body>
</html>

What Happens When You Run This:

  1. As the page loads, you’ll first see an alert box:
    • “Welcome to JavaScript!”
  2. After dismissing the alert, check your browser console (F12 or right-click > Inspect > Console): You’ll see:
    • “This runs from the head.”
  3. On the web page, you’ll see the text:
    • Hello World!!

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