Dispelling Responsive App Testing Myths

There’s been a lot of buzz about Firefox’s Responsive Design View and to a lesser extent Chrome’s User Agent swapper. These built-in, ready-to-go tools are awesome and huge time savers for web developers. But, they are NOT a substitute for testing your app across multiple browsers and on different devices.

A highly simplified definition of responsive design is it lets your web app dynamically adjust content based on screen height, width and pixel density. There are over a dozen responsive frameworks including Twitter Bootstrap, 960 Grid, jQuery and Titan. The number of them has exploded in recent years and it’s a daunting task to figure out which ones meet your project’s needs. So, the intent of this blog post is to provide some super simple, quick guidelines for getting started with testing your apps against them.

What does Firefox’s Responsive Design View do? It lets you change the dimensions of your application on-the-fly and even rotate it by simply clicking a button. Very cool! It lets you pretend to see what your app will look like on different screen sizes. In the latest versions of Firefox, you can access this view via Tools > Web Developer > Responsive Design View.  See the screenshot for an example of what the tool looks like.

What does Responsive Design View not do? It does not emulate the actual functionality of browsers on different sized devices. So, simply swapping screen sizes on your Windows desktop Firefox browser is not a valid substitute for physically testing your app on a tablet or smartphone. Firefox offers a separate download for Firefox on Android if you want to test on a mobile device.

What does a user-agent do? The user-agent is intended to identify a browser to a webserver or web application. It is sent by the browser in the HTTP request header. The agent can be parsed and used to determine if any specific actions need to be taken within an application. So, if you are using Chrome you can spoof using Internet Explorer 9. Here’s an example of a user-agent for Firefox running on Windows 7 64-bit:

Mozilla/5.0 (Windows NT 6.1; WOW64; rv:16.0) Gecko/20100101 Firefox/16.0

The most common use of user-agents on webservers is for creating site visit statistics that provide a generalized break-down of site visitors by browser type.

The most common use of user-agents in web applications is for determine how content is displayed and how JavaScript may be used in that browser. If you have some JavaScript that you know won’t work in IE, then you want to try and do your best to detect specific versions of IE to control your content.

Why spoof the user-agent? Simply put, it tricks an application into being displayed based on the user-agent characteristics. The key word is “display”. The user-agent spoof does not emulate actual browser functionality. It only shows you what the app looks like if it contains browser-specific code by tricking it into thinking it’s running on a specific browser. However, to properly test full browser functionality you need an actual install of the browser on a specific device and operating system.

Is user-agent detection reliable? In general, no. User-agent detection within your code is not reliable. Because user-agents can be easily spoofed these days, it is no longer a single reliable source for determining how your application will display content. Even jQuery, for example, recommends against relying on user-agents as a sole means of determining browser type.

For JavaScript, it’s usually best to check to see what is supported by a particular JavaScript library, for example in jQuery.

$("p").html("This frame uses the W3C box model: <span>" +
jQuery.support.boxModel + "</span>");

Or, if you are building larger applications consider a special detection library like Modernizr that helps with HTML, CSS and JavaScript coding patterns.

What about CSS3 Media Queries? CSS3 Media Queries are considered to be an integral part of responsive design coding patterns. They let you use CSS to detect certain characteristics of a browser in order to adjust the styling of an application by doing things such as swapping visibility of HTML elements or even adding or removing DIVs from the layout. Using Firefox’s Responsive Design tool or Chrome’s user-agent swapper can be used to test these elements with a healthy dose of caution. You still need to do your final testing for browser-specific functionality on the respective browsers themselves. Here is an example of a media query looking for maximum and minimum screen width:

@media screen and (min-device-width:768px) and (max-device-width:1024px) {
    /* styles go here */

You can also run media queries from within JavaScript:

var portraitMatch = window.matchMedia("(orientation: portrait)");
function orientationChangeHandler() {
  if (portraitMatch.matches) {
    // Portrait orientation
  } else {
    // Landscape orientation

Using Media Queries is considered a best practice when used in conjunction with a feature detection library such as Modernizr, or feature detection coding patterns to validate if a CSS feature works on a particular browser.  Feature detection code may be the way to go if you are only detecting a handful of CSS3 attributes and don’t need the extra weight of a full blown library like Modernizr, for example:

if (document.createElement("detect").style.borderRadius === "") {
    //TODO if borderRadius detected

if (document.createElement("detect").style.WebkitBorderRadius === "") {
    //TODO if webkitBorderRadius detected

Debugging Web Apps on Android’s Mobile Browser – Part 2

In addition to the suggestions listed in Part 1, I forgot to mention one more tool. There is a lesser known browser that can be quite handy for debugging: Firefox mobile. This relatively unknown sibling of the full-blown desktop browser actually has a fairly nice, built in debugger. The one major caveat is that it doesn’t work as well as the native browser for HTML5, CSS3 and some JavaScript, but it may be just the tool you need for some quick debugging, on-the-fly. Besides it fits in your pocket along with your other mobile apps, and you don’t need Logcat.

Step 1 – place your finger in the middle of the screen and drag it to the left. Click the gears icon at the bottom right of the screen.

Step 2 – In the upper right hand corner of the next screen, click the bug icon

Step 3 – Scroll down the datagrid to view errors.

The 1 Minute Primer for HTML 5

HTML 5 is getting a lot of press these days and I get a constant stream of questions from many non-techies, as well as developers, asking me to explain HTML5 in layman’s terms. So here it is.

HTML 5 is really a combination of three things: HTML, CSS and JavaScript. When all three of these technologies work together in a web browser then you have an HTML5 application. Period.

Why should we care about HTML 5? HMTL 5 brings many long awaited enhancements that make it easier for web developers to build more complex applications. More importantly, HTML 5 is being adopted by the major browser vendors: Google, Microsoft, Mozilla and Apple and this adoption is making it possible for developers to take advantage of the latest web technology that are built into web browsers.

How is HTML 5 “built into a web browser”? Web browsers have to interpret a web page first, and then display the content for you. Browsers contain logic that let’s them parse a pages’ code, and that code provides instructions for the browser to do certain things. Behind the scenes, in fact, the page you are looking at is built using code. It’s the browser that interprets the code and displays it in a way that makes sense to you. If you haven’t ever seen web page code then you can usually select View > Source on your browsers tool bar. Cool, right?!

HTML 5. HTML 5 is the latest version of the Hypertext Markup Language (HTML) specification which has been around in various forms since approximately 1991. HTML is a tag based language that defines the meaning and placement of elements of a web page. For example, a <button> tag defines a clickable button on a web page.

Cascading Style Sheets (CSS). Cascading Style Sheets, or more specifically CSS version 3 (a.k.a CSS3), provide the ability to apply styling to HTML elements. An example of styling would be to change the color of an HTML <button> from grey to green, as well as defining where on a web page it will be visible such as the top left corner.

JavaScript. JavaScript, which is really the meat behind HTML 5, is a type of programming language that lets developers implement actions within a web page. An example of an “action” would be when a web page visitor clicks a button that loads a picture. So, HTML defines the <button>, CSS styles the button, and JavaScript handles the action behind the scenes by retrieving the picture and then telling the browser how to display it for the end user.

This all sounds great, are there any downsides? Yes. First, HTML 5 is a standards-based specification that is still a work in progress. The specification and all its’ associated parts won’t be finalized for some time, possibly years. The good news is that browser vendors are keen to adopt this standard as much as possible. Second, implementation across different browsers isn’t 100% consistent. The good news is that there are tools and online resources to help developers work around many of these problems. Last, older versions of browsers (e.g. Internet Explorer 7 or 8, older versions of Safari, etc) don’t support HTML 5. There are strong campaigns under way to educate people to upgrade for security, performance and viewing experience.

So, there you have it. That’s a cursory pass at HTML 5 and I hope this post helps. I’ve added a few links at the bottom if you want to learn more about it.

Learn More:

 HTML5Rocks.com – includes information on features, tutorials and great slide decks.

w3Schools.com –  includes live “Try it” samples that let you explore the functionality.

W3C HTML 5 Specification –the World Wide Web Consortium is the group that writes the standards. If you are a techie, this is “the” specification that the browser vendors base their functionality on.

Top Five Resources for HTML5 Developers

Whether you are just learning about HTML5 or you’re cranking out code and don’t want to be slowed down, this is my 2012 short list of definitive HTML5, CSS3 and JavaScript resources that you need right now, at your fingertips, as you’re developing apps. I suggest bookmarking all of these web sites. If you use other sites that rock, please leave a comment with links below!

  1. Canisuse.com – This is an awesome comprehensive site where you simply type what feature you are looking for in the search box and the page will show a table outlining which browsers support that feature.
  2. HTML5Rocks.com – From interactive presentations and tutorials to code playgrounds, this site is a great place to learn more about HTML5.
  3. W3Schools.com – Excellent resource for beginners and experts. This site has embedded “Try it yourself” samples that you can modify on the fly. This site also includes a handy HTML5 tag reference
  4. CSS3.info – Previews, module status, articles…this site is a great resource for all things CSS3.
  5. W3C HTML4 vs HTML5 Comparison – this is the constantly updated, definitive source of what’s different between the two specifications.

And while not in my top five, I also have to give an honorable mention to Html5please.us and findmebyip.com. I’ve found that these sites are not as complete as caniuse in terms of the total number of features listed. But, I like them as a double check for browser support.

Holy Grail Resources:

W3C – W3C HTML 5 Specification – The World Wide Web Consortium is the group that writes the standards for HTML.

WHATWG.orgHTML Living Standard This is the technology working group that makes initial recommendations to the W3C.

[Updated broken links: Dec 6, 2016, Apr 5, 2017]