Example on jQuery Event Bubbling Situation

Abhimanyu K Vatsa
Mar 14, 2012

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Introduction

Before getting started here, please review the last article [Simple Style Switcher using jQuery and CSS-Part 2], so that you can understand the basics of the jQuery code used in this article.

Complete Page Code (You will find Event Bubbling Situation in this code):

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="Default2" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>Exploring jQuery</title>
    <script src="Scripts/jquery-1.4.1.js"
            type="text/javascript"></script>
    <style type="text/css">
        .hidden { display: none; }
        .hover { cursor: pointer; background-color: Red; }
    </style>
    <script type="text/javascript">
        //Mouse Hover
        $(document).ready(function () {
            $('#SwitchDIV b').hover(function () {
                $(this).addClass('hover');
            }, function () {
                $(this).removeClass('hover');
            });
        });
        //Hiding DIV
        $(document).ready(function () {
            $('#SwitchDIV').click(function () {
                    $('#SwitchDIV p').toggleClass('hidden');
            });
        });
    </script>
</head>
<body>
    <div id="SwitchDIV" style="background-color: Aqua;">
        <b>Switchable DIV</b>
        <p>
            <button>Some Action</button>
            <br />
            Welcome to the Student's Section.
            Please enter your Enrollment No. and Password
            ( type the Enrollment Number and Password as per the official records )
            to access this section and to know the status of New admission/
            Re-registration. In case of any difficulty in accessing the information,
            contact us.
        </p>
    </div>
</body>
</html>

Look at the following animated image, that shows how it will look when the above code runs.

Please note, I wish to collapse the DIV when clicking on the "Switchable DIV" text but the above system fails to do that as it also gets collapsed when I click on the button; that's because of Event Bubbling. The event is first handled by the button, then passed up through the DOM tree until it reaches the <div id="SwitchDIV" style="background-color: Aqua;">, where our new handler is activated and collapses (hides) the <p>.

Now, to solve this problem we need to access the event object. This is a DOM construct that is passed to each element's event handler when it is invoked. It provides information about the event, such as where the mouse cursor was at the time of the event. It also provides some methods that can be used to affect the progress of the event through the DOM.

To use the event object with the above code, we only need to add a parameter to the function and use it with an if condition. Here you go.

        //Hiding DIV
        $(document).ready(function () {
            $('#SwitchDIV b').click(function (event) {
                if (event.target == this) {
                    $('#SwitchDIV p').toggleClass('hidden');
                }
            });
        });

In the above code, I made some modifications that you can easily understand if you read the previous articles or compare the code with the above code where we fall in Event Bubbling.

Now, again run the program; you will get the desired actions; find my working screen below.