Home > Articles > Programming

Get Started with jQuery: First Examples

This chapter from Learning jQuery: A Hands-on Guide to Building Rich Interactive Web Front Ends provides just a few working examples of jQuery and demonstrates central key facts of jQuery.

Read Learning jQuery: A Hands-on Guide to Building Rich Interactive Web Front Ends and more than 24,000 other books and videos on Safari Books Online. Start a free trial today.

This chapter is from the book

In this chapter, we make first contact with jQuery without any further preparations.In other words, we are jumping right into the deep end. I am anxious for you to get a feeling for what you can do with jQuery and what you can get out of this framework. Just accept for now that many questions regarding the source text have to remain open at this stage. Don’t worry, though; these questions are answered over the next few chapters. The explanations on the listings also remain somewhat superficial at this stage, to avoid going off topic. We want to get into the practical application of jQuery as quickly as possible and just have some fun playing around, which means creating examples.

2.1. Accessing Elements and Protecting the DOM

If you already have some basic knowledge of programming on the Web,1 you already know that you can access the components of a web page via JavaScript or another script language in the browser via an object model with the name Document Object Model (DOM). For this type of access, there are several standard techniques,2 each of which has its own weaknesses. In particular, you usually have to enter many characters when accessing just a single element of the web page (or a group). This involves a lot of effort and is susceptible to errors. Most frameworks therefore offer a system via which this access can take place with an abbreviated, unified approach. Plus the underlying mechanisms compensate for various weaknesses of the standard access methods, above all by compensating for browser-dependent particularities and supplementing various missing functions of the pure DOM concept. Particularly important is that this compensation has generally been tested on all officially supported browsers and therefore works rather reliably.

The following example demonstrates another extremely important function of jQuery—protecting the DOM. More on what this is all about later. For now, let’s just say that different browsers process the web page differently on loading (parsing) the page, which can lead to a number of problems when the elements of the web page are accessed (especially if you try to access the elements of the web page too soon in a script—in other words, before the browser has correctly constructed the DOM). Here, jQuery offers a reliably method for mastering these problems.

The example also shows you in passing, as it were, how you can use jQuery as a standardized way of accessing contents of elements with text and reacting to events. But enough introduction. Here is our very first listing (ch2_1.html):3

Listing 2.1. The First jQuery Example

02 <html xmlns="http://www.w3.org/1999/xhtml">
03  <head>
04    <meta http-equiv="Content-Type"
05      content="text/html; charset=utf-8" />
06    <title>The first jQuery example</title>
07    <script type="text/javascript"
08        src="lib/jquery-1.8.min.js"></script>
09    <script type="text/javascript">
10      $(document).ready(function(){
11        $("#a").click(function(){
12          $("#output").html("Boring :-(");
13        });
14        $("#b").click(function(){
15          $("#output").html("A nice game :-)");
16        });
17        $("#c").click(function(){
18          $("#output").html("A strange game. " +
19               "The only winning move " +
20             "is not to play.");
21        });
22      });
23    </script>
24  </head>
25  <body>
26    <h1>Welcome to WOPR</h1>
27    <h3>Shall we play a game</h3>
28    <button id="a">Tic Tac Toe</button>
29    <button id="b">Chess</button>
30    <button id="c">
31      Worldwide Thermonuclear War</button>
32    <div id="output"></div>
33  </body>
34 </html>

Just create the HTML file in a separate directory and save it under the listed name.

In practice, you would usually save all your resources that are part of a project within a separate directory. For a web project, the best solution is to create these directories in the shared folder of your web server. In the case of Apache/XAMPP, this is usually the directory htdocs. This has the advantage that—if the web server is running—you can run the test directly via HTTP and a proper web call, not just load the file via the FILE protocol into the browser (in other words, the classic opening as file or simply dragging the file into the browser). The latter is not a realistic, practice-related test because later the pages also have to be requested by the visitor via a web server.

If you are working with an integrated development environment (IDE) such as Aptana or the Visual Studio Web Developer, you can usually display a web page directly from the IDE via an integrated web server. In Aptana, this is done via the Run command, and in Web Developer (a Firefox add-on) you can use the shortcut Ctrl+F5.

In lines 7 and 8, you see the reference to an external JavaScript file—the jQuery library that in this specific case resides in the subdirectory lib of the project directory where the website is saved. This structure has now become widely accepted in practice. This means that the jQuery library also has to be located in exactly that place. But, of course, you can instead choose to use a different path structure.

Figure 2.1

Figure 2.1. In this project, the jQuery library is located in the directory lib, seen from the perspective of the website.

Line 9 to 23 contains a normal JavaScript container. In it, the web page is addressed with $(document) (line 10). The function $() is a shorthand notation for referencing an element of the web page. You also see these shortened access notations in lines 11, 12, 14, 15, 17, and 18. But here, an element ID is used as a parameter.

Let’s now take a quick look at the method ready() that starts in line 10 and goes up to line 22. This method ensures that the calls it contains are only executed when the web page has been fully loaded and the DOM is correctly constructed. As hinted at before and without going into too much detail, this is already a feature whose value cannot be appreciated highly enough.

Within the ready() method, three event handlers each specify the reaction when clicking the listed elements. In our examples, these are three buttons marked with a unique ID.

The allocation to the correct function is achieved via the ID and triggering the function within the method click(). Note that we are using an anonymous function here (without an identifier).

It also gets interesting if a user clicks one of the buttons. This displays a specific text output in a section of the web page. We are again using $() and an ID for selecting the section (a div block) and the method html() for accessing the content.

Figure 2.2

Figure 2.2. The web page with the three buttons; the user has just clicked the third button.

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020