SO - 22706172

HTML

<form method="post" id="form" action="admin/insertShoutBox">
    <input type="hidden" name="user_id" id="user_id" value="1" />
    <input type="hidden" name="user" id="nick" value="admin" />
    <p class="messagelabel">
        <label class="messagelabel">Message</label>
        <textarea id="message" name="message" rows="2" cols="80"></textarea>
    </p>
    <div class="buttons">
        <button type="submit" class="positive" name="submit" value="submit">
            <img src="http://localhost/kaimonokago3/assets/icons/disk.png" alt="disk" />Save</button>
    </div>
</form>

JavaScript

$(document).ready(function () {
    //global vars
    var inputUser = $("#nick");
    var inputMessage = $("#message");

    //check if all fields are filled
    function checkForm() {
        if($.trim(inputUser.val()) && $.trim(inputMessage.val())) {
            return true;
        } else {
            return false;
        }
    }


    //on submit event
    $("#form").submit(function (event) {
        event.preventDefault();
        if (checkForm()) {

        } else alert("Please fill all fields!");
        //we prevent the refresh of the page after submitting the form
        return false;
    });
});