Onsubmit_Form_Validation.html

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>&#x1F3F4;&#x200D;&#x2620;&#xFE0F; Complete Javascripts Course</title>
    <link href="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/css/bootstrap.min.css" rel="stylesheet"
        integrity="sha384-Vkoo8x4CGsO3+Hhxv8T/Q5PaXtkKtu6ug5TOeNV6gBiFeWPGFN9MuhOf23Q9Ifjh" crossorigin="anonymous" />
</head>

<body onload="startImg()">
    <br />
    <br />
    <br />
    <br />
    <br />
    <center>
        <!-- <input type="text" id="item"> -->
        <br />
        <div id="wrapper">&#x1F4C3; &#x1F3EA; 👾 </div>
        <br />
        <form action="index2.html" method="get" onsubmit="return valForm()"> First:
            <input type="text" id="firstName">
            <br><br> Last:
            <input type="text" id="lastName">
            <br><br> Age:
            <input type="text" id="age">
            <br><br>
            <input class="btn btn-outline-info" type="submit" value="submit"> </form>
        <script>
            function valForm() {
                var p = event.target.children;
                if (p.firstName.value == "") {
                    message("Needs a first Name!!");
                    return false;
                }
                if (p.lastName.value == "") {
                    message("Needs a last Name!!");
                    return false;
                }
                if (p.age.value == "") {
                    message("Needs an Age!!");
                    return false;
                }
                console.log(p.firstName);
                return true;
            }

            function message(m) {
                document.getElementById('wrapper').innerHTML = m;
            }
        </script>
        <script src="https://code.jquery.com/jquery-3.5.0.js"
            integrity="sha256-r/AaFHrszJtwpe+tHyNi/XCfMxYpbsRg2Uqn0x3s2zc=" crossorigin="anonymous"></script>
        <script src="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/js/bootstrap.min.js"></script>
        <script src="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/js/bootstrap.bundle.min.js"></script>
</body>

</html>