You know what jQuery Mobile is, the history of it as well as its features and goals. Now we're actually going to build our first jQuery Mobile website (well, web page) and see how easy it is to use.
In this chapter we will:
Create a simple HTML page
Add jQuery Mobile to the page
Make use of custom data attributes (data-*)
Update the HTML to make use of the data attributes jQuery Mobile recognizes
You can find all the source code for this chapter in the c1 folder of the ZIP file you downloaded from Github. If you wish to type everything out by hand, we recommend you use similar file names.
Let's begin with a simple web page that is not mobile optimized. To be clear, we aren't saying it can't be used on a mobile device. Not at all. But it may not be usable on a mobile device. It may be hard to read (text too small). It may be too wide. It may use forms that don't work well on a touch screen. We don't know what kinds of problems will have at all until we start testing. (And we've all done testing of our websites on mobile devices to see how well they work, right?)
Lets have a look at
Listing 1-1: test1.html <html> <head> <title>First Mobile Example</title> </head> <body> <h1>Welcome</h1> <p> Welcome to our first mobile web site. It's going to be the best site you've ever seen. Once we get some content. And a business plan. But the hard part is done! </p> <p> <i>Copyright Megacorp © 2012</i> </p> </body> </html>
You can also download the example code files for all Packt books you have purchased from your account at http://www.packtpub.com. If you purchased this book elsewhere, you can visit http://www.packtpub.com/support and register to have the files e-mailed directly to you.
Wow, that's pretty tiny. You've probably seen web pages like this before on your mobile device. You can, of course, typically use pinch and zoom or double click actions to increase the size of the text. But it would be preferable to have the page render immediately in a mobile friendly view. This is where jQuery Mobile enters.
In the preface we talked about how jQuery Mobile is "just" a set of files. That isn't said to minimize the amount of work done to create those files, or how powerful they are, but to emphasize that using jQuery Mobile means you don't have to install any special tools or server. You can download the files and simply include them in your page. And if that's too much work, you have an even simpler solution. jQuery Mobile's files are hosted on a Content Delivery Network (CDN). This is a resource hosted by them and guaranteed (as much as anything like this can be) to be online and available. Multiple sites are already using these CDN hosted files. That means when your users hit your site they will already have the resources in their cache. For this book we will be making use of the CDN hosted files, but just for this first example we'll download and extract the bits. I recommend doing this anyway for those times when you're on an airplane and wanting to whip up a quick mobile site.
To grab the bits, visit http://jquerymobile.com/download. There are a few options here but you want the ZIP file option. Go ahead and download that ZIP file and extract it. (The ZIP file you downloaded earlier from Github has a copy already.) The following screenshot demonstrates what you should see after extracting the files from the ZIP file:
Important note: At the time this book was written, jQuery Mobile was preparing for the release of Version 1.1. The released version was 1.0.1. But with 1.1 so close to release, that version is in use. Obviously, by the time you read this book a later version may be released. The file names you see listed in the previous screenshot are version specific, so keep in mind they may look a bit different for you.
1. First add the HTML 5 doctype to the page:
<!DOCTYPE html>. This is used to help inform the browser about the type of content it will be dealing with.
2. Add a viewport metatag:
<meta name="viewport" content="width=device-width, initial-scale="1">. This helps set better defaults for pages when viewed on a mobile device.
Let's look at a modified version of our previous HTML file that adds all of the above:
For the most part, this version is the exact same as
So while nothing changed in the code between the
body tags, there is going to be a radically different view now in the browser. The following screenshot shows how the Android mobile browser renders the page now:
Right away you see a couple of differences. The biggest difference is the relative size of the text. Notice how much bigger it is and easier to read. As we said, the user could have zoomed in on the previous version, but many mobile users aren't aware of this technique. This page loads up immediately in a manner that is much more usable on a mobile device.
As we saw in the previous example, just adding in jQuery Mobile goes a long way to updating our page for mobile support. But there's a lot more involved to really prepare our pages for mobile devices. As we work with jQuery Mobile over the course of the book, we're going to use various data attributes to mark up our pages in a way that jQuery Mobile understands. But what are data attributes?
<div id="mainDiv" data-ray="moo">Some content</div>
In the previous HTML, the
data-ray attribute is completely made up. However, because our attribute begins with
data-ray attribute and change the background color to whatever was specified in the value.
This is where jQuery Mobile comes in, making extensive use of data attributes, both for markup (to create widgets) and behavior (to control what happens when links are clicked). Let's look at one of the main uses of data attributes within jQuery Mobile - defining pages, headers, content, and footers:
Compare the previous code snippet to
listing 1-2 and you can see that the main difference was the addition of the
div blocks. One
div block defines the page. Notice it wraps all of the content inside the
body tags. Inside the
body tag, there are three separate
div blocks. One has a role of "header", another a role of "content", and the final one is marked as "footer". All the blocks use
data-role which should give you a clue that we're defining a role for each of the blocks. As we stated above, these data attributes mean nothing to the browser itself. But let's look what at what jQuery Mobile does when it encounters these tags:
Notice right away that both the header and footer now have a black background applied to them. This makes them stick out even more from the rest of the content. Speaking of content, the page text now has a bit of space between it and the sides. All of this was automatic once the
div tags with the recognized
data-roles were applied. This is a theme you're going to see repeated again and again as we go through this book. A vast majority of the work you'll be doing will involve the use of data attributes.
In this chapter, we talked a bit about how web pages may not always render well in a mobile browser. We talked about how the simple use of jQuery Mobile can go a long way to improving the mobile experience for a website. Specifically, we discussed how you can download jQuery Mobile and add it to an existing HTML page, what data attributes mean in terms of HTML, and how jQuery Mobile makes use of data attributes to enhance your pages. In the next chapter, we will build upon this usage and start working with links and multiple pages of content.