11. HTML Form Validation Example.

    <!DOCTYPE html>
    <html>
    <head>
        <script>
            function validateForm() {
                var x = document.forms["myForm"]["fname"].value;
                if (x == "") {
                    alert("Name must be filled out");
                    return false;
                }
            }
        </script>
    </head>
    <body>
        <form name="myForm" onsubmit="return validateForm()">
            Name: <input type="text" name="fname">
            <input type="submit" value="Submit">
        </form>
    </body>
    </html>

Output

        No Output Available