Home > Articles

📄 Contents

  1. The Goals of HTML5
  2. Requisites for HTML5 Development
  3. Summary
  • Print
  • + Share This
This chapter is from the book

This chapter is from the book

Requisites for HTML5 Development

This section covers a few important considerations for developing HTML5 web apps. These represent nothing new to a seasoned web developer but are otherwise important for understanding the rest of this book.

Modern Browser Developer Tools

Browser developer tools have matured rapidly over the past six years. For both developers and designers, it is strongly recommended that you familiarize yourself with them, as they are referenced occasionally in this book.

Specifically, this book utilizes the JavaScript console in many of its examples, which is used to log messages. This increases the simplicity of the book’s code examples because we can create sample output without bothering with HTML page manipulation. We output to the console with the JavaScript method console.log(someOutput).

Developer tools are typically launched via a Settings menu, or with the command Ctrl+Shift+I, or just F12 depending on the browser. The JavaScript console is found within most developer tools.

The developer console is very flexible, and can also be used to manipulate JavaScript on a page or merely for JavaScript experimentation. Writing directly into the console evaluates the statement and then provides its return value on the next line. Figure 2.1 shows the JavaScript console within the developer tools for Chrome and Firefox, with console-access buttons highlighted and a few commands entered.

FIGURE 2.1

FIGURE 2.1. Chrome and Firefox with their developer tools open, with the console showing. Buttons to show/hide the console are indicated with arrows.

This book also mentions newer features of developer tools that specifically aid in debugging some HTML5 features, like local storage and web workers. These are referenced and explained in their respective chapters.

The importance of learning browsers’ developer tools cannot be stressed enough. Familiarizing yourself with them is one of the most important job skills of web developers today. Chrome’s developer tools are top notch, and Firefox has very recently (March 2013) debuted a huge amount of useful new functionality to its toolset.

HTML5 Fallbacks: Shims, Shivs, and Polyfills

You’ll find the terms shim, shiv, and polyfill peppered throughout HTML5 resources. Where HTML5 is concerned, the three words represent roughly the same concept: a JavaScript library that provides HTML5-like functionality to older browsers, reproducing the native functionality as closely as possible.

In their most generous form, shims and polyfills are drop-in libraries that allow you to use HTML5 features without worrying about proper support for older browsers. The polyfill library detects these unsupporting browsers and attempts to re-create a particular HTML5 feature’s functionality through JavaScript or other means. At the least, these libraries ensure that new HTML content is styled correctly on older browsers.

For a few years, the lack of support in older browsers stalled implementation of HTML5 features. Today, barring impossible-to-reproduce functionality in some features, HTML5 features can safely be used without fear of leaving older browsers in the dust.

Online, you will be able to find a good deal of these polyfill libraries and very good lists of such libraries, such as the one in the Modernizr project: https://github.com/Modernizr/Modernizr/wiki/HTML5-Cross-browser-Polyfills (the project itself is mentioned later in this chapter). Chapter 3 also contains a section on some of the most popular HTML5 polyfill libraries.

Feature Support and Detection

Not every HTML5 feature can be reasonably supported with a polyfill. For some features, such as complex canvas applications, it is necessary to support a different kind of fallback. In the case of canvas, that usually entails displaying an image instead of a dynamic animation or a “sorry, please consider upgrading your browser” message instead of interactive content.

How Do I Know What Features Are Supported?

Before you use any particular HTML5 feature, it’s a good idea to look at a website of compatibility tables to see which browser versions currently support the feature. There are several of these websites, and the most popular ones are as follows:

  • caniuse.com
  • html5please.com
  • mobilehtml5.org

Figure 2.2 shows a typical compatibility table from caniuse.com. You can see that all versions of Internet Explorer and many mobile browsers do not support WebGL, the 3D specification for HTML5 canvas (2D canvas is much more widely supported).

FIGURE 2.2

FIGURE 2.2.Compatibility table from caniuse.com showing WebGL support on major browser versions.

Always Use Feature Detection

Sometimes you’ll want to use a feature even if some browsers do not support it and there is no reasonable fallback. Instead of attempting to detect particular unsupporting browsers, it is always better to detect the existence of features.

For instance, the HTML5 canvas element is not supported on Internet Explorer 8 or below. To test for its support, you could create a canvas element and then check for one of the methods that you would expect to exist:

var supportsCanvas = document.createElement('canvas').getContext != undefined;

The variable supportsCanvas will be true in Internet Explorer 9 and false in Internet Explorer 8. Using document.createElement('canvas') alone is not enough because it will successfully create an element of type HTMLUnknownElement. Instead, you check to see if the getContext method exists on the new element.

There are many other valid ways to test for canvas support (or most HTML5 features for that matter), and instead of bothering to find a working method for each, it is sometimes easier to use a library. The most popular feature detection library is Modernizr (modernizr.com), which can quickly detect all HTML5 and CSS3 (Cascading Style Sheets) features and enable you to respond by executing some appropriate JavaScript, or even conditionally loading different JavaScript and CSS files based on a feature’s support.

  • + Share This
  • 🔖 Save To Your Account

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.

Overview


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.

Surveys

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.

Newsletters

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.

Security


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

Children


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

Marketing


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.

Choice/Opt-out


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.

Links


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