Developing Mobile Web Apps: When, Why, and How

There are 6.8 billion people on the planet, 5.1 billion of whom own a cell phone (source). And today, an ever-growing percentage of these devices are smartphones. According to a recent Pew Research Center Study, the number of users accessing the Internet on their smartphones has more than doubled in the past 5 years, as has the number of users downloading and using mobile apps. Of those who use the Internet or email on their phones, more than a third go online primarily through their handheld devices.

Indeed, mobile computing is becoming increasingly ubiquitous… and it’s awesome.

Except, of course, when it’s not.

As a mobile device user, few things are as frustrating and difficult to fat-finger-navigate as a poorly designed mobile web or native app.

And as a mobile app developer, few things can be as intensely irritating as striving to support as wide a range of mobile clients as possible, each of which has its own frustrating set of idiosyncrasies. Whether you choose to develop a mobile web, native, or hybrid app, the quest to support multiple mobile browsers, more-exotic devices, and platforms can be quite a gut wrenching experience indeed.

Of course, not every developer today needs to worry about supporting mobile clients. But the increasingly omnipresent nature of mobile devices and applications strongly suggests that those who don’t need to support mobile clients today will more than likely need to do so in the not-too-distant future. So if you’re not already thinking about mobile app development, you probably should be.

Mobile app: Web vs. native vs. hybrid (help me choose!)

As is true with most technology selections, there’s no one-size-fits-all answer when it comes to the type of mobile app to develop. There are numerous web app best practices to consider, not all of which are technical. Who is your target audience? Are they more likely to prefer a mobile web or a native app? What development resources do you have and which mobile technologies are they most familiar with? What is the licensing and sales model that you’re envisioning for your product?

Generally speaking (although there are always exceptions), the mobile web route is faster and cheaper than the native app route, especially when the objective is to support a wide range of devices. Conversely, there may be capabilities native to the mobile device (such as the movement sensor and so on) that are essential to your app, but which are only accessible via a native app (which would therefore make the mobile web app choice a non-starter for you).

And beyond the web vs. native question, a hybrid app may be the right answer for you, depending on your requirements and resource constraints. Hybrid apps, like native apps, run on the device itself (as opposed to inside a browser), but are written with web technologies (HTML5, CSS and JavaScript). More specifically, hybrid apps run inside a native container, and leverage the device’s browser engine (but not the browser) to render the HTML and process the JavaScript locally. A web-to-native abstraction layer enables access to device capabilities that are not accessible in mobile web applications, such as the accelerometer, camera, and local storage.

But whatever choice you make – whether it be mobile web, native or hybrid app – be careful to adequately research and confirm your assumptions. As an example for the purposes of this mobile web app development tutorial, you may have decided to develop a native app for e-commerce to sell your products, but according to Hubspot, 73% of smartphone users say they use the mobile web more than native apps to do their shopping… so you may have bet on the wrong horse.

And then, of course, there are the practical considerations of time and budget. As one of my favorite sayings goes, “faster, better, cheaper… pick any two”. While time-to-market and cost constraints are of paramount importance in web application development, it’s crucial not to compromise too heavily on quality in the process. It’s quite difficult to recover the confidence of a user who has had a bad first experience.

Indeed, mobile web, native, and hybrid apps are all radically different beasts, each with their own unique set of benefits and challenges. This development tutorial specifically focuses on methodologies and tools to employ, and pitfalls to avoid, in the development of highly functional, intuitive, and easy-to-use mobile web applications.

Plan ahead (“if you don’t know where you’re going, you just might end up there…”)

Identifying your (or your customer’s) requirements is one of the most essential best practices in app development, mobile or otherwise. Carefully research the targeted capabilities to determine if they are achievable in a web app. It’s quite frustrating, and highly unproductive, to realize that one or more of your essential client functions aren’t supported, when you’ve already invested the time and resources to design the web-based interface and supporting infrastructure.

Another common gotcha for mobile web app developer newbies is to ass-u-me that web-based code for a desktop browser will work “as is” in a mobile browser. Not. There most definitely are differences and, if you’re not aware of them, they can definitely bite you. The HTML5 <video> tag’s autoplay functionality, for example, doesn’t work on mobile browsers. Similarly, the CSS transition and opacity properties are not supported (or at least are not consistently supported) in most mobile browsers nowadays. You will also have problems with some web API methods on a mobile platform, such as the SoundCloud music streaming API that requires Adobe Flash which is not supported on most mobile devices.

A particularly complicating factor in mobile web application development is that the lifespan of mobile devices tends to be much shorter than that of desktop displays (the average lifespan of a cell phone in the U.S. is around 21 months). These shorter device life spans, accompanied by constant releases of new mobile devices and technologies, yield an ever-changing landscape of to-be-targeted devices. While working in a browser does somewhat alleviate this issue by shielding you from a number of device-specific issues, you will still need to design a browser-based view that supports many different screen resolutions (as well as adjusting appropriately for landscape and portrait orientations).

Thought needs to be given as well to supporting Apple’s Retina Displays (liquid crystal displays that have a pixel density high enough that the human eye is unable to discern individual pixels at a typical viewing distance). Several Apple products – including the iPhone, iPod Touch, iPad, MacBook Pro, iPad Mini, and iPad Air – offer Retina displays. For a mobile web app in particular, it’s important to be aware that a Retina display makes low resolution images (which are typically served to mobile devices) look fuzzy and pixelation can occur. The best app development solution in these cases is to have the server recognize that the request is coming from a Retina device and to then provide an alternate higher resolution image to the client.

If you want to use some of the cool HTML5 stuff, remember to verify in advance that the functionality you’re looking for is supported across the device landscape that your customers are likely to be using. For example, in iOS 6 and above, there is no support for the navigator getUserMedia functionality since the camera is only accessible through native apps. Two great resources for checking what’s supported on specific devices and browsers are caniuse.com and html5test.com.

CSS3 media queries can also help you provide customized content for each device. Here’s some example code for capturing different device characteristics, such as pixel density, screen resolution, and orientation:

/* For lower than 700px resolutions */
@media (max-width: 700px) { ... }
/* Same as last but with the device orientation on land scape */
@media (max-width: 700px) and (orientation: landscape) { ... }
/* Including width and orientation you can add a media type clause,
   in this case 'tv' */
@media tv and (min-width: 700px) and (orientation: landscape) { ... }
/* for low resolution display with background-image */
.image {
    background-image: url(/path/to/my/image.png);
    background-size: 200px 300px;
    height: 300px;
    width: 200px;
}
/* for high resolution (Retina) display with background-image */
@media only screen and (min--moz-device-pixel-ratio: 2),
only screen and (-o-min-device-pixel-ratio: 2/1),
only screen and (-webkit-min-device-pixel-ratio: 2),
only screen and (min-device-pixel-ratio: 2) {
    -repeat;
        background-size: 200px 400px;
    /* rest of your styles... */
    }
}

Performance, performance, performance

“OMG, this thing is sooooo slow!” As a mobile web app developer, those are probably the very last words you ever want to hear from one of your users. You must therefore think carefully about how to reduce and optimize each byte and server transfer to reduce the user’s wait time. It’s unrealistic to expect that transfers will always be done over a WiFi network, and you should know that 60% of mobile web users say they expect a site to load on their mobile phone in 3 seconds or less (source). Similarly, Google found that, for every extra 5 seconds of load time, traffic dropped by 20% (and it is also worth noting that search engines look at load times as part of their calculation of page quality score).

As a part of this web app development tutorial, here are a few tips that can help optimize the performance of your mobile web app and minimize latency:

• Image Optimization. Image load time is well-known to be one of the biggest performance issues affecting page load on mobile devices. Use of online image optimizers, such as smushit.com, can be helpful in addressing this issue.
• Code compression. Compressing your JavaScript and CSS files, depending on the amount of code you have, can potentially have a significant impact on performance. A useful tool for compressing your code is refresh-sh.com.
• Database queries.
  • Some mobile device browsers don’t accept as many cookies as desktop browsers do, which can result in the need to execute even more queries than usual. Server-side caching is therefore especially crucial when supporting mobile web app clients.
  • Remember to employ the appropriate filters to preclude SQL query injection that could otherwise compromise the security of your site and server.
• Content delivery networks (CDN). If you are planning to provide lots of videos, images, audio files, or other types of media, use of a CDN is highly recommended. Some of the more common commercial CDNs include Amazon S3, Microsoft Windows Azure, and MaxCDN. The advantages of using a CDN are numerous and include:
  • Improved download performance. Leveraging a CDN’s resources enables you to distribute load, save bandwidth, and boost performance. The better CDNs offer higher availability, lower network latency, and lower packet loss. Moreover, many CDNs provide a globally distributed selection of data centers, enabling downloads to occur from a server closer to the user’s location (resulting in fewer network hops and faster downloads).
  • More concurrent downloads. Browsers typically limit the number of concurrent connections to a single domain, after which additional downloads are blocked until one of the previous downloads has completed. You can often see this limit in action when downloading many large files from the same site. Each additional CDN (on a different domain) allows for additional concurrent downloads.
  • Enhanced analytics. Many commercial CDNs provide usage reports that can supplement your own website analytics and which may offer a better quantification of video views and downloads. GTmetrix, for example, has an excellent website reporting tool for monitoring and optimizing the sources loaded on your site.

Your mobile web app development toolbox

“The right tools for the right job” is an age-old adage that applies as much to software development as it does to any other domain. This tutorial provides and introduction to some of the more popular and widely-used tools for mobile web app development, but bear in mind that there may very well be other tools that are the “right” ones for developing your mobile web app, depending on your requirements and available resources.

This article originally appear in Toptal