Twitter Bootstrap for responsive, mobile first web apps

This blog is no longer updated. Please refer to my new account: http://sanderrossel.com

Welcome back! As you may know I’ve just finished my series on starting web development and it was a huge success! I’ve got a lot of good feedback, so thanks everyone. If you have no idea what I’m talking about you can visit the first part of my web development series here: Web development #1: Internet and the World Wide Web.
So to stay in the spirit of web development I decided to do some blogs on popular libraries and frameworks. This week I’m going for Twitter Bootstrap (from now on I’ll call it just Bootstrap).
Speaking of Twitter, I just created a Twitter account to share interesting articles and industry news, so be sure to follow me @sanderrossel.
I also got myself a GitHub account where I’ll upload the code files for my blogs. You can find my GitHub at https://github.com/SanderRossel. The files for this particular blog can be found at the bootstrap-blog repository.
Yes, I’m doing the best I can to serve your every programming needs!

Bootstrap basics

Now let’s talk about Bootstrap. Bootstrap is a free and open-source front end CSS and JavaScript framework developed at Twitter. It was first released as open-source in 2011, version 2 came in 2012 and currently we’re at version 3, which is also the version I’ll be using in this post. One remark on the Bootstrap versions, there’s quite a difference between Bootstrap 2 and Bootstrap 3. If you’ve already worked with Bootstrap 2 and want to migrate or have an overview of the differences you may want to have a look at the Migration guide at Bootstrap.
As you may have guessed you don’t need any server software to use Bootstrap, so I’ll keep the examples here simple so you really don’t have to do anything else than create some files and run them in your browser.

So what does Bootstrap actually do? Simply said it allows you to easily layout your page using classes and HTML attributes. It’s mostly just CSS. Bootstrap does this using a grid on your page. Not an actual HTML grid, but a virtual grid, containing twelve columns that you can use to divide your content. So it may look something like this.

An example of how your Bootstrap columns can be organized.

An example of how your Bootstrap columns can be organized.

And of course you can use any number of columns, up to twelve, on any row. So how did I do this? Let’s look at some HTML.

<div class="container">
    <div class="row">
        <div class="col-xs-12">12 columns wide</div>
    </div>
    <div class="row">
        <div class="col-xs-6">6 columns wide</div>
        <div class="col-xs-6">6 columns wide</div>
    </div>
    <div class="row">
        <div class="col-xs-8">8 columns wide</div>
        <div class="col-xs-4">4 columns wide</div>
    </div>
    <!-- etc... -->
</div>

Here you can clearly see how I define rows and columns to layout my page (more on that later). Your columns don’t have to add up to twelve. If you have less than twelve columns there’ll just be an empty spot on your page and if you go over twelve columns Bootstrap will simply wrap your excess columns on a new line (but it’s best if you avoid this). If you need more or less than twelve columns for your page you can download the LESS version of Bootstrap and edit the columns variable. Very cool, but I’m not discussing that here.
So here are a few rules, rows need to be inside a .container (for fixed width) or .container-fluid (for full width) for proper alignment and padding. You should place only columns inside your rows and content within columns.

Other than that Bootstrap adds theming to your website. There are a lot of themes, both free and premium, that you can use to give your website a complete new look without having to change your HTML. And Bootstrap has a lot of controls for HTML, like dropdowns, buttons, navbars, tabs, etc. We’ll look at some of them later.

Creating a responsive page

So now that we know what Bootstrap can do for us let’s put this into practice. First of all let’s look at a very basic Bootstrap document. You can actually get it from the Bootstrap site. I’ve removed some stuff from it (mostly comments) that we aren’t going to use (mostly backwards compatibility for IE). You can view the original basic template at Twitter Bootstrap – Getting started.

<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="utf-8">
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <title>Hello, Bootstrap!</title>

        <link rel="stylesheet" href="css/bootstrap.min.css">
    </head>
    <body>
       <h1>Hello, Bootstrap!</h1>

       <script src="js/jquery-2.1.3.min.js"></script>
       <script src="js/bootstrap.min.js"></script>
    </body>
</html>

As you can see I’m assuming your HTML file is in a folder that contains a folder called css which contains the bootstrap.min.css file and a folder called js which contains bootstrap.min.js and jquery-2.1.3.min.js. You can get Bootstrap from the download section at Bootstrap and jQuery from the jQuery website. Bootstrap uses some jQuery for certain components, but you might not need it. If you do need it make sure you use a compatible version of jQuery. Other than that the meta element with the viewpoint may be unfamiliar to you. You should use this for websites that are optimized for mobile devices (don’t use it for non-responsive pages though).

So now that we have the basic Bootstrap template let’s display some text on the page. Let’s say we’re creating a news website and we want the cover story at the top and page wide. Beneath that we want some featured articles. And what’s more, we want it to look good on any device. So let’s say we have two rows, one for the cover story and one for the featured articles, that will be displayed next to each other. We can also safely assume that the number of featured articles that fit on the page is limited by our screen size. On a big screen we can have four featured articles next to each other, but on a medium and small sized screen we want maybe only three or less articles. Well, that’s something Bootstrap is really good at! So in the example above I’ve used col-xs-* to create a row that spans * columns. The xs here is the trick. It actually means that this row spans * columns on any device that’s xtra small (xs) or larger (because we didn’t specify what should happen if it gets larger). We have col-lg-* (large, anything larger than or equal to 1200 pixels), col-md-* (medium, anything larger than or equal to 992px), col-sm-* (small, anything larger than or equal to 768 pixels) and col-xs (extra small, anything smaller than 768 pixels). Most phones go into the xs category, tablets would be small or medium, laptops medium or large and desktops large. So then let’s see some HTML. For our news site we can have the following body (actual content left out).

<div class="container">
    <div class="row">
        <h1>Sander's bits</h1>
        <p>Writing the code you need</p>
    </div>
    <div class="row">
        <div class="col-xs-12">
            <h2>Main article</h2>
            <article><p>...</p></article>
        </div>
    </div>
    <div class="row">
        <div class="col-lg-3 col-md-4 col-sm-4">
            <h3>First featured article</h3>
            <article><p>...</p></article>
            </div>
        <div class="col-lg-3 col-md-4 col-sm-4">
            <h3>Second featured article</h3>
            <article><p>...</p></article>
        </div>
        <div class="col-lg-3 col-md-4 col-sm-4">
            <h3>Third featured article</h3>
            <article><p>...</p></article>
        </div>
        <div class="col-lg-3 hidden-md hidden-sm">
            <h3>Fourth featured article</h3>
            <article><p>...</p></article>
        </div>
    </div>
</div>

Let’s figure this bit out, eh? First of all I’m using a container, or a div element with the .container class to hold my rows. One thing about the container is that it’s sized differently on different screen sizes. So next I’m creating a row to hold my page name, which is Sander’s bits. Then comes the second row with our cover story. It’s spanned out across all twelve columns on all devices. Now comes our third row, which is the most interesting. Each article has multiple classes, one for each device size that we want to cover. On large devices we display four articles, each spanning three (out of twelve) columns (.col-lg-3). On medium sized devices the fourth article gets hidden (using the .hidden-md class) and the other three articles now span four columns (.col-md-4). Small devices have the same layout as medium sized devices (.hidden-sm and .col-sm-4). On extra small devices we don’t specify any layout and our page will display the articles one under the other (including the fourth). You can test this by opening the page in your browser and then simply changing the size of your browser window. Check at what size your browser hides or displays the fourth article and at what sizes it places the articles under each other.
I admit that’s quite some classes on your elements, and it may take you a bit to figure out what’s going on, but you get a lot in return. I don’t know about you, but I find this pretty amazing!

Bootstrap classes

Our news website is starting to look pretty professional already, but we want the cover story to stand out a bit more. Bootstrap adds all kinds of classes that you can use to style your page. For our cover story we’re going to add two: .lead and .text-center.

<h2 class="text-center">Main article</h2>
    <article><p class="lead text-center">...</p></article>

You may have guessed, but there are also the classes .text-left and .text-right and all they do is align your text to the left, right or center.
Looking good, right?

Let’s ‘mute’ the tagline too, it’s not all that important, so we want it to be visible, but not stand out too much.

<p class="text-muted">Writing the code you need</p>

Now what kind of news website doesn’t have weather forecasts? Let’s add some! I’m thinking of adding an HTML table to the bottom right. It’ll show up under our third or fourth column (depending on screen size). Luckily we can use offsets for our columns in much the same way we can make them span multiple columns. So let’s have a look at that table. Notice that I’m using HTML 5, which means we need table, thead and tbody elements. So the following HTML goes at the bottom of our container.

<div class="row">
    <div class="col-lg-3 col-lg-offset-9 col-md-4 col-md-offset-8 col-sm-4 col-sm-offset-8">
        <h4>Weather</h4>
        <table>
            <thead>
                <tr>
                    <td>Day</td>
                    <td>C&deg;</td>
                </tr>
            </thead>
            <tbody>
                <tr>
                    <td>Today</td>
                    <td>30</td>
                </tr>
                <tr>
                    <td>Tomorrow</td>
                    <td>25</td>
                </tr>
                <tr>
                    <td>Day after tomorrow</td>
                    <td>27</td>
                </tr>
            </tbody>
        </table>
    </div>
</div>

So the table is positioned right across all devices. The .col-lg-offset-*.col-md-offset-* and .col-sm-offset-* work great (and of course there’s also a .col-xs-offset-*). I don’t need to explain this, because you already know how it works. The table itself is rather clumsy though. The columns are pushed against each other and it doesn’t scale well at all. Bootstrap has a really very simple solution, just add the .table class. And because we want some additional styling we’re also going to add the .table-striped and .table-bordered classes.

<table class="table table-striped table-bordered">

Very nice! Now in that same style I also want to add some stock information on our page. And let’s indicate whether a stock went up, down or stayed the same. We can do this using the .success, .danger and .info classes (there’s also .warning and .active). These classes can be applied to buttons, text, table rows, labels, etc. The Bootstrap team has actually made sure these classes are consistent across elements for Bootstrap 3. So without any further explanation here’s our stock table (I just made up the numbers, don’t buy or sell based on this table).

<div class="row">
    <div class="col-lg-3 col-lg-offset-9 col-md-4 col-md-offset-8 col-sm-4 col-sm-offset-8">
        <h4>Stock</h4>
        <table class="table table-bordered">
            <thead>
                <tr>
                    <td></td>
                    <td>Price</td>
                    <td>%Change</td>
                </tr>
            </thead>
            <tbody>
                <tr class="success">
                    <td>Dow</td>
                    <td>18,128</td>
                    <td>0.94%</td>
                </tr>
                <tr class="danger">
                    <td>Nasdaq</td>
                    <td>5,026</td>
                    <td>-0.69</td>
                </tr>
                <tr class="info">
                    <td>S&P 500</td>
                    <td>2,108</td>
                    <td>0.00</td>
                </tr>
            </tbody>
        </table>
    </div>
</div>

So again, this is pretty simple, but the effects are amazing.

Let’s add an image to our main article to make it stand out even more. Bootstrap has some classes to handle images. Now what is the internet all about? If you answered cats you’re right! So let’s add a picture of my parent’s cat. We can add some classes to make it look good and have it scale with our screen size. I’m going to add the class .img-circle to make it round (alternatives are .img-rounded for round corners and .img-thumbnail). I’m also adding .img-responsive so it will resize with my screen. Last, but not least I’m adding the .center-block class to, well, center it.

<h2 class="text-center">Main article</h2>
 <article>
 <img src="http://sanderrossel.com/wp-content/uploads/2015/03/Cid.jpg" alt="My cat, Cid!" class="img-responsive img-circle center-block">
 <p class="lead text-center">...</p></article>

Bootstrap components

At this point you have to look pretty hard to see if you’re looking at the New York Times website or at our Bootstrap example page because our page is looking so good and professional. I’m still not completely happy though. I want my weather forecast and stock information to be tabbed. I’ve given an example of this before using jQuery UI in a previous blog post, Web development #6: Getting interactive with JavaScript, but this time we’ll be using Bootstrap to get the same effect. As mentioned before Bootstrap needs jQuery for certain components, the tab control is one such component. Compared to jQuery UI Bootstrap has some pros and cons. The pro is that we don’t need to write a single letter of JavaScript. The con is that the HTML is rather, well, bloated. You can remove the entire row containing the stock table and add the stock table to the row with the weather table. Then we need to tab both tables. So let’s look what it looks like.

<div class="row">
    <div class="col-lg-3 col-lg-offset-9 col-md-4 col-md-offset-8 col-sm-4 col-sm-offset-8">
        <ul class="nav nav-tabs">
            <li class="active">
                <a href="#weather" data-toggle="tab">Weather</a>
            </li>
            <li>
                <a href="#stock" data-toggle="tab">Stock</a>
            </li>
        </ul>
        <div class="tab-content">
            <div class="tab-pane active" id="weather">
                <!--Weather table goes here-->
            </div>
            <div class="tab-pane" id="stock">
                <!--Stock table goes here-->
            </div>
        </div>
    </div>
</div>

So like with jQuery UI we need an unordered list with the .nav and .nav-tab classes and anchor tags that link to the id’s of some div elements. The div elements containing our tab pages go into another div element that has the .tab-content class and is placed directly under the tab list. The data-toggle attribute tells Bootstrap what kind of component this is, a tab. Another cool feature are the tab pills and vertical tabs. Try changing the .nav-tabs class into .nav-pills or .nav-stacked. Looking pretty good!

Finally, let’s add a menu to our page. Adding a menu to any website can be pretty difficult. It needs to stay at the top, it needs to scale, you want some components to be left-aligned, others right-aligned, it’s just quite difficult. Bootstrap makes it a lot easier, but even then it’s not exactly easy. You need lots of classes, lots of elements, and just lots of everything really. It’s still easier than doing everything yourself and it scales really nice. So here’s what I’ve done. I’ve taken the example from the Bootstrap website and I’ve stripped it a bit. I’ve removed some buttons and dropdowns and some HTML attributes and classes that have to do with accessibility (for people with disabilities, like bad sight or even blindness).
We can create a navigation bar using the nav element. Within this nav element we’re going to create a fluid container, meaning it spans our entire page. After that we’re going to specify what our menu looks like when it’s collapsed, for example on phones, and what elements we like to show. So how about our brand, for which Bootstrap has some special classes, a search form, an About link and a Login button? The HTML would look like this (placed directly under your opening body tag).

<nav class="navbar navbar-default">
    <div class="container-fluid">
        <div class="navbar-header">
            <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#menu">
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
            </button>
            <a class="navbar-brand" href="http://sanderrossel.com" target="_blank">Sander's bits</a>
        </div>

        <div class="collapse navbar-collapse" id="menu">
            <form class="navbar-form navbar-right" role="search">
                <div class="form-group">
                    <input type="text" class="form-control" placeholder="Search">
                </div>
                <button type="submit" class="btn btn-default">
                    <span class="glyphicon glyphicon-search"></span>
                </button>
            </form>
            <ul class="nav navbar-nav navbar-right">
                <li><a href="#">About</a></li>
                <li><a href="#">Login</a></li>
            </ul>
        </div>
    </div>
</nav>

So check that out and look what happens when you resize your browser window. Awesome!

I’ve also used a glyph icon in my search button. This is another Bootstrap goodie. You can use glyphs like that to make your page just a little prettier. Actually, I want that for my weather and stock tabs too. Let’s change that.

<ul class="nav nav-tabs">
    <li class="active"><a href="#weather" data-toggle="tab"><span class="glyphicon glyphicon-cloud"></a></li>
    <li><a href="#stock" data-toggle="tab"><span class="glyphicon glyphicon-stats"></span></a></li>
</ul>

Nice, right?

There’s lots more that Bootstrap has to offer. We’ve already seen quite a bit and we got some pretty amazing results. The best part is that we got those results without writing a single line of JavaScript! What else can Bootstrap do? Well, it has more classes you can use to style your elements, like Code, Forms and Buttons. It has more components you can use, like Buttongroups, Button dropdowns, Breadcrumbs, Page headers, Alerts and Progress bars. And if you don’t like how your website looks try one of these free Bootstrap themes or check out these premium Bootstrap themes. If you like to know more about Bootstrap I can recommend two free books by SyncFusion, Twitter Bootstrap Succinctly (which is about Bootstrap 2) and Twitter Bootstrap 3 Succinctly (which is both an update and an addition to the first book).

You can find the entire HTML for this blog and the necessary CSS and JavaScript files on my GitHub account in the bootstrap-blog repository.

Happy coding!

Web development #8: Where to go from here

So if you’ve read all of my previous posts and you’ve made it this far congratulations! You’ve now learned the basics of web development and you have the knowledge to create awesome websites. To actually create awesome websites you need skills and skills come from practice and experience. I’ve only touched the surface in this blog series. So it’s now up to you to get your hands dirty and write more HTML, more CSS, more PHP and more JavaScript. And while doing that Google is your friend! I’ve far from discussed all the possibilities (people write entire books about that), but at least you know all the moving parts. So these previous blogs weren’t so much about making you a pro, they were about getting you up to speed in a simple manner. The rest, unfortunately, is up to you. In case you’ve missed some posts, here they all are again.

  1. Web development #1: Internet and the World Wide Web
  2. Web development #2: Our first website using HTML
  3. Web development #3: Styling our page with CSS 3
  4. Web development #4: PHP in the back
  5. Web development #5: User input with HTML Forms
  6. Web development #6: Getting interactive with JavaScript
  7. Web development #7: Dynamic page updates with AJAX
  8. Web development #8: Where to go from here

So what’s left for us? Well, in this post I’ll write about some stuff I haven’t written about in the previous posts, but which every web developer should know about. After that I’ll lay out some alternative technologies for you that may help you get started with the technologies you want.

Debugging

So you’ve written your page, you test it in your browser, and for some reason it doesn’t do what you want it to do. How can we find our error? The examples I’ve given were pretty small and in those cases it may be feasible to just have a good look at your code again. However, when you’re going to write large applications with much more code on both front- and back end just looking at your code isn’t going to help you. I haven’t discussed debugging your code because a lot of it depends on your environment. In this series I’ve used Notepad++ which doesn’t have any debugging capabilities (although I read there’s some plugin that let’s you debug code, I haven’t tried it though). If you’re going for an IDE (Integrated Development Environment) such as Visual Studio, Eclipse, NetBeans or XCode you’ll get a lot more possibilities. You can set breakpoints, for example, which allows you to pause your software on a certain line of code and inspect variables and their values and then even step through your code line by line to follow the flow of your code. Personally I work with Visual Studio and it allows you to see the entire stack and even edit code at run time.

But that’s all back end debugging. What if something is wrong with your CSS, HTML or JavaScript? Luckily all major browsers (and probably the non-major too) have debugging support. If you’re in IE, Firefox or Chrome press F12 and you’ll get the developer tools (alternatively you can look them up in the browser’s menu). So here you should see a tab or button that gets you to the console. In the console you’ll see any errors or warnings that are generated by your page (invalid HTML, a bug in your JavaScript, etc.). You can also log to the console yourself using console.log() in your JavaScript (never ever use that in production code though). There’s also a tab called Network where you can see all server requests from your page. This comes in handy when pages load slow, perhaps you’re making a lot of requests or you’re loading some large file that takes a while to load. There’s also a tab where you can see your page’s HTML and CSS and edit them real-time (in your browser, not on the server). You can either select an element in the DOM and have it light up on your page or select something on your page and have it highlighted in the DOM. Then you can make changes to your HTML and CSS and see the results real-time. It’s also possible to debug your JavaScript. You can set breakpoints and step through the code following the execution flow and inspecting your variables. Pretty neat and indispensible when working on your pages! Try working with the developer tools in your browser of choice and look for some tutorials.

Picking a back end language

In this series I’ve used PHP. PHP is free (although most languages are nowadays), easy to start with and supported everywhere. You can simply open up Notepad(++), start typing PHP, put it on your server and it’ll run. Compare that to other (compiled) languages like Java and C# and PHP is an absolute winner. A lot of popular Content Management Systems (CMS), applications that help in creating, editing, publishing and maintaining content on your websites, such as WordPress, Joomla!, Drupal and Magento, have support for PHP too. So PHP is a good choice for many applications.

However, a lot of people prefer their languages more strongly typed and object oriented. In that case you might go for Java or C# (or Visual Basic). So suppose you want to go for C# because perhaps you already have experience in WinForms or WPF or a client wants a .NET application. So when using C# you’re basically using the .NET Framework and when going for web development you’ll be using the ASP.NET stack. But then in ASP.NET you’ll have some options like WebForms and MVC. Let’s go with ASP.NET MVC, because that’s a good choice for modern web development. ASP.NET MVC makes use of the MVC Design Pattern. MVC stands for Model View Controller. When requesting a page ASP.NET MVC basically calls a method on a class. This class is called the Controller. Perhaps your Controller makes some database calls and does some computations and then comes up with the data that you want to show on your page. This data is just another class and represents the Model. The Model is then passed to your View, which is basically your HTML, which is then returned to the client. And, like PHP, with C# (or Visual Basic) you can generate HTML/View using the Razor Engine.
So you want to get started with ASP.NET MVC? I don’t blame you, it’s a great product. I recommend you get the Visual Studio Community Edition for free and just start! There’s plenty of tutorials on the web, but if you’re looking for a more structured course on MVC I can recommend the book Professional ASP.NET MVC 5.
And here’s a little downside to .NET compared to PHP. Once you have your software ready for production you’ll need a server with .NET installed that’s also running some special server software called IIS (Internet Information Services).

Another alternative to PHP and C# is Node.js. Node.js is relatively new and is a fast and lightweight platform that allows you to run JavaScript in your back end and create real-time web applications. So you can use JavaScript in your back end, which is pretty neat because that means you can re-use code from your back end in your front end! Try doing that using any other back end language. Other than that Node.js uses sockets, which enables it to send data to your client without that client asking for it. Usually a client sends a request and the server serves. But now we can serve without the client having to request! That allows us to easily create, for example, a chat application. Our client simply subscribes to the chat and our server sends every new message to the client as soon as it’s received. So when going with Node.js you probably want to use Express as well. Express is a JavaScript framework for Node.js which makes working with Node.js just a bit easier. And when you want to start using sockets extensively you might want to check out Socket.IO, which is a library for working with sockets from JavaScript. And of course you’ll need to generate your HTML in Node.js. There’s a few options for you, but Jade is a pretty popular one.
So you may have figured out some of the downsides of Node.js. First of all, it’s JavaScript, which may or may not be a problem for you, depending on your tastes. Second, unlike C#, Node.js doesn’t “just work”. To get any serious business done you need quite some external JavaScript libraries (and there’s A LOT as we’ll see in a bit). The pro, of course, is fast, relatively easy, real-time web apps using the same language as your front end.
If you’re interested in Node.js you may take a look at what’s called the MEAN stack, MongoDB, Express, AngularJS and Node.js. It’s free, open-source and very JavaScript.

I should probably mention that .NET has their own sockets framework that allows you to build real-time web apps easily, called SignalR.

So we’ve looked at some alternatives to PHP. There are more, like Ruby (On Rails), Python and Java. You can check them out, read a bit about them, and decide what works well for you.

Some front end alternatives

So we’ve looked at some back end alternatives, but what can you do on the front end? On the front end it really all comes down to HTML, CSS and JavaScript. Your HTML is generated on your back end and there’s plenty of options to do it, like Razor, Jade or any other HTML generator. It all depends on what back end you pick.

So what about CSS? Well, browsers really require CSS to lay out your page. There are some alternatives though, most notably LESS.
LESS looks a lot like CSS, but adds some features. You could almost call it object oriented CSS.
Another alternative is Stylus, which, like LESS, adds features to CSS. Stylus is focusing more on expressive CSS, which is easy and clean to read while also supporting some form of object orientism.
There’s more, like Sass and Turbine.
Now here’s the deal. None of them replace CSS, rather they are compiled to CSS. So you write your LESS (or any other), compile it, then use the generated CSS on your page. This adds some hassle, since you need to compile your code (your not-quite-CSS) before you can actually see it on your page (as opposed to just refreshing your page). But they also make for clean, maintainble CSS. I recommend checking out at least one of them, especially when you’re going to build larger websites. Alternatively you can just use an already existing library, such as Twitter, which I’ll talk about in a bit.

What about alternatives for JavaScript? There are quite some languages that compile to JavaScript. The two most notable are probably TypeScript and CoffeeScript though.
When you read the first lines on the CoffeeScript page you’ll pretty much have an idea what CoffeeScript is all about, “JavaScript has always had a gorgeous heart. CoffeeScript is an attempt to expose the good parts of JavaScript in a simple way”. So there isn’t much to say about that. It’s just a new syntax for JavaScript, hiding the dirty bits. I haven’t used it myself, but if you don’t quite like the JavaScript syntax and want to try something that’s like JavaScript, but prettier you might want to check out CoffeeScript.
Now TypeScript, that’s quite something different. It adds type safety to JavaScript and actually reads more like C# than JavaScript. Not completely by coincidence as TypeScript was actually created by Anders Hejlsberg, lead architect of C#. Of course it still just compiles to JavaScript. If you’re already in the Microsoft stack and using Visual Studio you may as well give TypeScript a try!
I also want to mention Dart very briefly. It was created by Google and it’s a fully object oriented way of writing JavaScript. In their words “new, yet familiar”.

Libraries and Frameworks

When working with JavaScript you know everything is possible, but nothing is easy. Luckily a whole lot of people have created libraries for you that you can use when using JavaScript. In this section I just want to point out some popular libraries and frameworks. We’ve already seen jQuery and jQuery UI.
Another very popular framework is Twitter Bootstrap. It’s mostly CSS, but has some JavaScript too. It allows you to create pages that look good and scale well across devices with relative ease. It mostly depends on tagging your HTML elements correctly. I’m not going to discuss it any further here. Just know that it’s available and that it’s widely used.
Another popular library is Knockout. With Knockout you can bind your JavaScript classes to your HTML elements. So values are automatically synchronized between your HTML and JavaScript. If a user changes the value of a text field the underlying value is changed and is reflected on your page and vice versa. Again, I’m not discussing it further, just know that it exists.
Another library that you simply cannot ignore is AngularJS. AngularJS is an MVVM (Model View ViewModel) framework for building Single Page Applications (SPA). That means you get a single web page and all data is fetched using AJAX. It makes for a fluent user experience as the website doesn’t need to refresh with each request (only parts of it). AngularJS is BIG. It basically does most that jQuery does and everything that Knockout does as well and the learning curve can be steep. Luckily there are some nice tutorials and books around.
Now one of the most awesome JavaScript libraries you’ll come across is D3.js. If you need any kind of graph or table, or any visual to represent your data, D3.js is the library you need. Just look at it. The website features many examples and it’s fun to just look at it. The only thing I don’t like about this library is that I haven’t needed it yet 🙂
You might come across Ember.js as well. It’s an MVC framework for creating Single Page Applications.
Without going into detail, here are some other popular JavaScript libraries: Underscore.js, Backbone.js, MooTools, jQuery Mobile, Modernizr

There’s literally thousands of JavaScript libraries and frameworks. Some are pretty big, like Angular, and some are really small and do just one thing only, but do it really well. You might want to check out Microjs, a website with literally hundreds of very small JavaScript files. Just look around and see what’s available, it might surprise you.

Some final words

So in this final post of my web development series we’ve looked at some alternatives and libraries you can use to help you create awesome websites. There’s still lots of stuff that we haven’t covered, like putting your website in production (because that really depends on the languages you used and where you’re hosting), security (very important!) and SEO, or Search Engine Optimization. We’ve also skipped databases entirely.
We did have a look at all the parts that are vital in web development though. You should now have a pretty good idea of what you need to create your own websites.
In this series I have pointed out some books from the SyncFusion Succinctly Series, and I’m going to do so again. You can subscribe freely and gain access to free books on JavaScript, Twitter, Knockout, AngularJS, Node.js and much more. All I can say is that it’s really worth it!
For more (less succinct) books on various topics, including a lot of web development, I can recommend Manning Publications. They have some good stuff on Node.js, D3.js, SPA Design, CORS, and more.
Two other really cool articles/projects I came across are Learn JavaScript by Dave Kerr, where he creates a Space Invaders game using JavaScript and a Mario game by Florian Rappl. Both are worth checking out (and if you don’t like their articles you can still play the games 😉 ).

So that’s it for this series. That isn’t to say I’ll stop blogging or I’ll stop writing about web development, it just won’t be for this series. I hope you enjoyed it as much as I did. Any comments and questions are more than welcome!

Thanks for reading.

Happy coding!

Web development #7: Dynamic page updates with AJAX

So in theory you should now have all the tools to create the most awesome websites. However, I don’t think any tutorial on web development is complete without doing some AJAX. No idea what I’m talking about? Read my previous posts.

  1. Web development #1: Internet and the World Wide Web
  2. Web development #2: Our first website using HTML
  3. Web development #3: Styling our page with CSS 3
  4. Web development #4: PHP in the back
  5. Web development #5: User input with HTML Forms
  6. Web development #6: Getting interactive with JavaScript
  7. Web development #7: Dynamic page updates with AJAX
  8. Web development #8: Where to go from here

So what is AJAX all about? It’s an abbreviation for Asynchronous JavaScript And XML. It enables us to send a request to the server and receive a result without having to refresh our entire page. Now that’s pretty awesome! What’s also pretty awesome is that we don’t need to use XML. As Linus Torvalds, creator of Linux, already said “XML is crap. Really. There are no excuses. XML is nasty to parse for humans, and it’s a disaster to parse even for computers. There’s just no reason for that horrible crap to exist.” So what we’ll be using is a form of AJAX called AJAJ, where the last J stands for JSON (JavaScript Object Notation). To make it a bit more confusing, we’ll just call it AJAX anyway. Oh yeah, and it doesn’t have to be asynchronous either…

JavaScript objects and JSON

First of all we need to know what JavaScript Objects are and what they look like. After that JSON will come naturally. So JavaScript has objects and much like objects in other languages JavaScript objects are just wrappers around certain functionality. The difficulty in JavaScript, of course, lies in that anything can be anything and then can become anything else… Let’s just look at an example.

// Creates an empty object.
var obj = {};
// Gives the object a firstName property.
obj.firstName = 'Sander';
// Gives the object a lastName property.
obj.lastName = 'Rossel';
// Gives the object a getFullName function.
obj.getFullName = function () {
    return this.firstName + ' ' + this.lastName;
};

// Alternative for the above.
var person = {
    firstName: 'Sander',
    lastName: 'Rossel',
    getFullName: function () {
        return this.firstName + ' ' + this.lastName;
    }
};

Now this wouldn’t be JavaScript if we didn’t have even more methods to create objects (JavaScript also knows constructors). We’re not interested in those though. What we’re interested in is the second method I’m using. Notice that, to create an object, we use curly braces. We can then basically add anything to that object by simply defining keys (property or function names) and values (default values for properties or implementations for functions) seperated by colons. Each key and value is seperated by a comma. And of course objects can contain other objects too.

var outerObj = {
    innerObj: {
        someValue: null
    },
    anotherInnerObj: {
        innerInnerObj: {}
    },
    message: 'Phew, what syntax!'
};

You can work with objects as ways of namespaces so you can keep the ‘global namespace’ clean and minimize the chance for name conflicts with other libraries. Objects are also often used to create some sort of options that are given to a function. A function then simply checks if some property or method on the option object exists, what its value is, and acts accordingly. We’ll see this usage a little later when working with AJAX.

So then, what is JSON? It’s simply some text using almost the exact notation we just saw. So let’s look at some examples.

{
    "firstName": "Sander",
    "lastName": "Rossel"
}

{
    "innerObj": {
        "someValue": null
    },
    "anotherInnerObj": {
        "innerInnerObj": {}
    },
    "message": "Phew, what syntax!"
}

That’s looking pretty familiar now, doesn’t it? And, if you compare it to XML, it’s a lot more compact, saving you precious bits and bytes when you’re sending your data over the internet!

Making an AJAX request

So let’s look at an AJAX example. I’ll start very simple making a synchronous request that returns just plain text (so no XML or JSON) when the page loads. You’ll know that the request doesn’t refresh the page because if it would the page would keep refreshing (as it makes the request upon loading). Alternatively, you can track all requests your browser makes using your browsers developer tools (press F12 in IE, FireFox or Chrome and navigate to the Network tab). I’m using jQuery to get the page load event and to show the result of our AJAX request. So here’s the HTML (in a file called Ajax.html):

<!DOCTYPE html>
<html>
    <head>
        <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
        <script type="text/javascript" src="Ajax.js"></script>
    </head>
    <body>
        <p id="result"></p>
    </body>
</html>

Here’s our JavaScript (Ajax.js):

$(function () {
    var ajax = new XMLHttpRequest();
    ajax.open('GET', 'Ajax.php', false);
    ajax.send();
 
    $('#result').text(ajax.responseText);
});

And finally our PHP (Ajax.php):

<?php
    echo 'Result of AJAX request!';
?>

So all of these files go into the htdocs folder of your XAMPP installation and you’ll have to access your page by browsing to localhost/Ajax.html (notice I named all files ‘Ajax’). So what’s really interesting here is that in my JavaScript I’m using an XMLHttpRequest object. So we call the open method and pass in a string specifying the HTTP method, GET or POST. Next we’re telling it what URL to navigate to and last we’re specifying whether the request should be asynchronous (we’re calling it synchronous). Then we send the request to the server. So, because we’re calling it synchronous the browser blocks until we get response from the server. That means that on our next line of code we simply have our result, ajax.responseText. Now you’ll never do this, in fact, our browser even gives off a warning saying that this method is deprecated because it negatively affects the user experience. In our case we won’t notice the blocking, but if we’re downloading larger chunks of data our page will freeze up completely!

So let’s make that call asynchronous so the user can go about doing his business while our page gets our data for us. This isn’t actually to hard. We simply change our JavaScript to the following:

$(function () {
    var ajax = new XMLHttpRequest();
    ajax.onreadystatechange = function () {
        if (ajax.readyState == 4) {
            $('#result').text(ajax.responseText);
        };
    };
    ajax.open('GET', 'Ajax.php', true);
    ajax.send();
});

So I’m specifying an onreadystatechange function which gets called when the state of our ajax object changes. State 4 means it’s done and we can get the result.

Now there are quite some options we can set and check, but I’ll not get into that. You can check them on the XMLHttpRequest documentation page and play around with them yourself. Instead, we’re going to use jQuery to make AJAX requests.

Using jQuery for AJAX requests

You might be thinking if there’s anything jQuery cannot do? There’s actually plenty of stuff you don’t want to do using jQuery, but AJAX isn’t one of them. jQuery makes AJAX pretty easy actually. We were already using jQuery, so we can simply edit our JavaScript.

$(function () {
    $.ajax({
        type: 'GET',
        url: 'Ajax.php',
        complete: function (jqXHR) {
            $('#result').text(jqXHR.responseText);
        }
    });
});

So remember I was telling you about using an object to specify options? This is one such an example. We’re passing in an object and specify the type, the url and a function that will be called when the requests completes (jqXHR stand for jQuery XMLHttpRequest, but you can name it anything). We could’ve passed in much more, but we didn’t. So this does the same as the code we had earlier.

The jQuery.ajax function can actually do a whole lot of stuff! Next we’re going to pass in some parameters and echo them on our page.

$(function () {
    $.ajax({
        type: 'GET',
        url: 'Ajax.php',
        data: {
            artist: 'Led Zeppelin',
            song: 'Immigrant Song'
        },
        complete: function (jqXHR) {
            $('#result').text(jqXHR.responseText);
        }
    });
});

And now we need to alter our PHP too.

<?php
    if (isset($_REQUEST['artist']) &&
        isset($_REQUEST['song']))
    {
        $artist = $_REQUEST['artist'];
        $song = $_REQUEST['song'];
        echo "The song '$song' by $artist rocks!";
    }
?>

So that was pretty easy, right? We just passed in a JavaScript object with some properties and they were converted to parameters in our PHP automatically! So how does this work the other way around? This is where JSON comes into play! JSON stands for JavaScript Object Notation, so it should be pretty easy for JavaScript to create actual objects that we can use. So let’s start by modifying our PHP so that it returns JSON.

<?php
    class song
    {
        public $artist = NULL;
        public $name = NULL;
    }
 
    if (isset($_REQUEST['artist']) &&
        isset($_REQUEST['song']))
    {
        $song = new song();
        $song->artist = $_REQUEST['artist'];
        $song->name = $_REQUEST['song'];
 
        header('Content-Type: application/json');
        echo json_encode($song);
    }
?>

First of all, I’m using an object to store our data. We’ve seen this before. I’m setting our response header so that it tells our browser it’s json. Then I’m using the json_encode function to convert our object into JSON. If you now check out the result in your browser you’ll notice that we’ve received some actual JSON!

But what we really want is to use this JSON in our JavaScript as if it were just an object. Actually this is pretty easy! We can get the object from the XMLHttpRequest.

complete: function (jqXHR) {
    var song = jqXHR.responseJSON;
    $('#result').text("The song '" + song.name + "' by " + song.artist + " rocks!");
}

And that’s it. Alternatively, we can use the ‘success’ option, a function that passes us the returned data, the status of the request and the XMLHttpRequest.

$(function () {
    $.ajax({
        type: 'GET',
        url: 'Ajax.php',
        data: {
            artist: 'Led Zeppelin',
            song: 'Immigrant Song'
        },
        success: function (song, status, jqXHR) {
            $('#result').text("The song '" + song.name + "' by " + song.artist + " rocks!");
        }
    });
});

And likewise there is an ‘error’ option.

$(function () {
    $.ajax({
        type: 'GET',
        url: 'Ajaj.php',
        data: {
            artist: 'Led Zeppelin',
            song: 'Immigrant Song'
        },
        success: function (song, status, jqXHR) {
            $('#result').text("The song '" + song.name + "' by " + song.artist + " rocks!");
        },
        error: function (jqXHR, status, errorThrown) {
            $('#result').text('An error occurred: ' + jqXHR.status + ' ' + errorThrown);
        }
    });
});

Notice that I’m calling ‘Ajaj.php’, a page that doesn’t exist. Naturally we’ll get 404, Not found. When using the ‘complete’ option we used earlier you’d have to check for success yourself, our current implementation would actually break our page if we called ‘ajaj.php’.

So there’s actually quite a bit to think about when using AJAX. Did the server return a result, what kind of result did it return, was the request successful, etc. We can use the XMLHttpRequest object for this. Check ‘status’ to see if our request was successful (status 200 means success) and then ‘responseType’ and any of ‘response’, ‘responseText’, ‘responseJSON’ or ‘responseXML’ for the result.

Posting data

So in the previous examples we’ve taken a look at the GET method. In the next example I’m going to take our movies page we created in my previous blog posts, Web development #4: PHP in the back and Web development #5: User input with HTML Forms. So first of all we’ll have to edit the PHP file. We want the form to go, because that refreshes the page. We also want to add jQuery and a custom JavaScript file to our header. Last, we need to give some ids to some elements because now we need to update the page ourselves once we add a new movie (after all, the page isn’t refreshing). So without further delay, here’s the modified PHP.

<?php
    if (isset($_POST['movieName']))
    {
        $movieName = $_POST['movieName'];
        if ($movieName)
        {
            file_put_contents('movies.txt', htmlspecialchars($movieName) . "\r\n", FILE_APPEND);
        }
 
        exit();
    }
?>
<!DOCTYPE html>
<html>
    <?php
        function fileAsUnorderedList($fileName, $notFoundMessage)
        {
            if (file_exists($fileName))
            {
                echo '<ul id="movies">';
                $lines = file($fileName);
                foreach ($lines as $line)
                {
                    echo '<li>' . htmlspecialchars($line) . '</li>';
                }
                echo '</ul>';
            }
            else
            {
                echo $notFoundMessage;
            }
        }
    ?>
    <header>
        <title>My favourite movies!</title>
        <meta charset="utf-8">
        <meta name="description" content="A list of my favourite movies.">
        <meta name="keywords" content="Favourite,movies">
        <meta name="author" content="Sander Rossel">
        <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
        <script type="text/javascript" src="Movies.js"></script>
    </header>
    <body>
        <h1>My favourite movies!</h1>
        <p>
        <?php
            fileAsUnorderedList('movies.txt', 'No favourite movies found!');
        ?>
        </p>
        <h2>Add a movie!</h2>
        <div>
            <label for="movieName">Movie name</label>
            <input type="text" name="movieName" id="movieName" />
            <button id="submit">Submit</button>
        </div>
    </body>
</html>

And then we need to add a JavaScript file (I’ve called it Movies.js) to add an event handler to our button click event which takes the value of the input, posts it to the server and on success adds the movie to our list and empties the movie input.

$(function () {
    $('#submit').on('click', function () {
        var movieInput = $('#movieName');
        var movieName = movieInput.val();
        if (movieName) {
            $.ajax({
                type: 'POST',
                url: 'Movies.php',
                data: {
                    movieName: movieName
                },
                success: function (data, status, jqXHR) {
                    $('#movies').append('<li>' + movieName + '</li>');
                    movieInput.val(null);
                },
                error: function (jqXHR, status, errorThrown) {
                    alert("An error occurred while adding movie '" + movieName + "'.");
                }
            });
        };
    });
});

And there you have it. Looks complicated? I guess it is a bit, but once you get the hang of it it’s not so bad. And luckily the documentation is rather good!
Another cool addition to our page would be pagination. Let’s say we are going to add hundreds of movies. Getting those all in once might slow down our page quite a bit. So we can use AJAX to get just ten, or twenty, or fifty at a time. The page could load them on a button click or when we scroll to the end of the page (that is, get the movie titles and add them to our list using jQuery, also make sure you ‘remember’ what page you’re on). This principle is called pagination and can greatly enhance user performance (and for large websites it’s even a must).

So that’s it for AJAX. And actually, that’s it for web development! You’ve now seen everything involved in creating awesome, responsive web pages. Of course there’s still a long way to go as we’ve only scratched the surface of web development. We’ve seen the tools, but are by no means expert in any of them. In my next, and last, blog post I’ll give you some tips on frameworks and libraries that can help you create the pages you want.

Stay tuned!

Web development #6: Getting interactive with JavaScript

We’ve come pretty far by now! We’re almost there actually. After reading this post you should be able to create pretty awesome websites using the full web development stack! So what’s left for us to discover? We have seen we can build dynamic websites on the back end using PHP, but what about being dynamic once the page is loaded? Well that’s where JavaScript comes into play!

  1. Web development #1: Internet and the World Wide Web
  2. Web development #2: Our first website using HTML
  3. Web development #3: Styling our page with CSS 3
  4. Web development #4: PHP in the back
  5. Web development #5: User input with HTML Forms
  6. Web development #6: Getting interactive with JavaScript
  7. Web development #7: Dynamic page updates with AJAX
  8. Web development #8: Where to go from here

The websites we’ve build were all pretty amazing. We’ve started simple using just HTML, added some CSS, then we added some dynamic content and we could even upload our own content. I don’t know about you, but I think that’s pretty amazing. However, I still feel like our pages are missing a little… schwung! How about highlighting buttons, sliding content in and out of our page? Just some fancy visuals that will make our website stand out. JavaScript comes to the rescue.
As an added bonus we can make calls to our back end without refreshing the entire page using AJAX. More on that later, let’s look at some fundamentals first.

JavaScript fundamentals

JavaScript has been around since 1995. It’s easy to learn, but hard to master. I’m not going to spend a lot of time on the syntax because it looks (and behaves) a lot like PHP, including truthy and falsey). I’m just going to write code. Try to keep up. I’m still writing in Notepad++ by the way. We also won’t be needing XAMPP to run basic JavaScript in this post (we’ll be needing it later for AJAX though).

One thing you should know about JavaScript is that, like CSS, it can be embedded into your HTML. But we don’t want that. In my post about CSS we learned to keep HTML and CSS seperated, which makes it easier for you to remodel your page by simply replacing some CSS files. We’ll use the same approach for JavaScript.

So let’s take a look at our first example. Yes, it’s going to be Hello world! Not the most exciting example, but you’ll see JavaScript in action. So we start out by creating a very simple HTML file. Call it whatever you like.

<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <title>My first JavaScript!</title>
        <script type="text/javascript" src="MyJS.js"></script>
    </head>
    <body>
        <button onclick="sayHello();">Press me!</button>
        <p id="output"></p>
    </body>
</html>

And now in the same folder create a file called MyJS.js. Inside it put the following code:

function sayHello () {
    var output = document.getElementById('output');
    output.innerHTML = 'Hello JavaScript!';
}

So let’s look at both the HTML and JavaScript. First in the header of the HTML you’ll notice I’ve added a script element. In this element I define the type and src attributes. Pretty straightforward I think. Your HTML now simply loads the specified JavaScript. In an actual server-client environment this means that the JavaScript files are sent to the client together with the HTML page.
Other than that we see a button element with an onclick event. Now whenever the user presses a button an event fires. An event is simply a notification you can subscribe to. In this case we subscribe by specifying onclick and telling it we want the function sayHello to be executed.

Now this function, sayHello, is defined in our MyJS.js file. It does the following. We declare a variable called ‘output’ using the var keyword. We assign it the result of a function called getElementById that takes a string as input parameter and is defined on something called document. Now your document is a variable that your browser gives to you and it represents your HTML content. So we’re almost literally saying “document, give me the element with id ‘output'” and guess what it returns? Yes, our p element with id ‘output’! Now that we have our paragraph we can alter it any way we see fit. In this case I’m simply going to give it the text “Hello JavaScript!”.
There’s more functions like getElementById, like getElementsByName() and getElementsByClassName(). Once you have an element you can get its child elements (using children()), its parent element (using parentElement()), its ‘neighbouring’ elements (using previousSibling() and nextSibling()) and much more. What we’re basically doing is traversing and altering the DOM (Document Object Model, or your HTML document).

Now here’s why I like and dislike JavaScript. It took me about fifteen minutes to get this example running… Fifteen!? Yes. Why? Because I spelled ‘innerHTML’ as ‘innerHtml’ and what does JavaScript do? You might say it gives us an error saying innerHtml does not exist. Wrong, what it actually does is create innerHtml on the ‘output’ variable (or more precisely the object it references). It doesn’t do anything with it, it just sits there. But in the meantime innerHTML remains empty, my page doesn’t show “Hello JavaScript!” and I’m not getting an error of any kind.
So with JavaScript you can actually alter already existing objects! How cool is that? Pretty cool, but it can lead to very subtle and hard to troubleshoot bugs, so be careful. That is also why you should always use the var keyword when creating variables. Failing to do so will work fine, but will actually create a property on your this object (the object, or context, you’re currently operating in).

And that’s actually all I’m going to tell you about basic JavaScript. The standard library is actually pretty difficult to work with and you’ll often deal with bugs like the one I just described. To top it off different browsers can behave differently using the same JavaScript code. Luckily (and also a bit unlucky) there are literally thousands of libraries and frameworks that do all the hard stuff for us. One of those libraries has become so popular that it has become the de facto standard when working with the DOM, I’m talking about jQuery.

Getting started with jQuery

There are two ways to get jQuery included in our page. One we have already seen. We get the jQuery files from jQuery.com, put them on our server (or during development our local machine) and get them in our page using the HTML script element. There are two versions you can get, the regular or the minimized version. The regular version is great for development as it is easier to debug. The minimized version has all unnecessary characters like spaces, meaningful variable names, white lines etc. removed from the file, making them practically unreadable, but making the file a little smaller in size making it to load a bit faster on our webpage. A lot of libraries have regular and minimized versions.

For this example we’re going to use the second method to get jQuery in our page though, which is through a CDN, or Content Delivery Network. A CDN is just some host providing you with popular files you might need, like jQuery. A possible benefit of using a CDN is that they might have servers across the globe, which means that if someone in America is using our website hosted in Europe they could still get jQuery from a server near them. Another possible benefit is that you don’t have to host the file yourself. So if you can, use a CDN.
Popular CDNs are Microsoft and Google, so let’s go with the Google CDN.
One word of caution though. Whenever your website requests a file from any CDN the host of that CDN may track the users of your page (they’re making a request after all). So while this is probably no problem for your personal website, it may be an issue for corporate environments where privacy and security are of bigger importance.

Let’s have a look at how our header looks with jQuery from a CDN.

<head>
    <meta charset="utf-8">
    <title>My first JavaScript!</title>
    <script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
    <script type="text/javascript" src="MyJS.js"></script>
</head>

So you see, it actually looks the same, but we’re putting a link in the src attribute. Also notice that I put jQuery above MyJS because MyJS is going to need jQuery to run. Now let’s rewrite that sayHello function we had so it uses jQuery.

function sayHello() {
    var output = $('#output');
    output.text('Hello jQuery!');
}

Looks weird? $ is actually a perfectly valid function name in JavaScript and jQuery is utilizing it. $ is also called the jQuery function and alternatively you could’ve used jQuery(‘#output’). Now notice what we pass as a parameter to the jQuery function. It’s a CSS selector! Yes, you can get ANY element (or elements) on the page using CSS selectors. That’s great because we already know CSS. And when we have our output element we set the text (the part between the opening and the closing tags) to ‘Hello jQuery!’.

Now remember that I said we shouldn’t have JavaScript in our HTML? Well, we still have our onclick event in the button tag, so I guess I lied. JavaScript doesn’t really have a simple elegant solution to this problem. But jQuery does (they made it simple)! First of all let’s change our button tag so it doesn’t hard wire that onclick event.

<button id="btn">Press me!</button>

And next let’s take a look at our JavaScript.

$(document).ready(function () {
    $('#btn').on('click', sayHello);
});

function sayHello() {
    var output = jQuery('#output');
    output.text('Hello JavaScript!');
}

As you can see I’ve added a $(document).ready(function) call to our JavaScript page. That might look arcane, but it’s really simple actually. We call the jQuery function and pass it our document. We’re getting something back which obviously has a ready function that takes a function as parameter. This function, also called a callback function, is called when the document is ready (the HTML has loaded and is ready for traversal and manipulation). We then create an anonymous function to be called. It’s really the same as our sayHello function, except that we don’t give it a name. So in this anonymous function we get our button element and then call the on function on the result. With the on function we can hook up events to our elements. In this case we want the click event and we specify a function to be called when the click event fires (the button is clicked).
Here’s an alternative way of writing the above. I’m using a shorthand notation for $(document).ready by simply passing an (anonymous) function directly to the jQuery function.

$(function () {
    $('#btn').on('click', function () {
        $('#output').text('Hello jQuery!');
    });
});

Let that sink in. Study the syntax and compare the two examples. Take a look at how I rewrote the sayHello function to an anonymous function in particular, it may help understanding what’s going on. You may also want to try rewriting this using no anonymous functions.

There’s a whole lot to jQuery that I cannot show you in this blog, but the jQuery documentation is actually pretty good, so be sure to use it!

Now I’m going to show you another trick with which you can create beautiful pages using classes and CSS. First create a CSS file called MyStyle.css and add the following style to it:

.hovering {
    color: white;
    background-color: blue;
}

Now let’s create a single paragraph we want to light up once you hover your mouse over it. Don’t forget to link your stylesheet!

<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <title>My first JavaScript!</title>
        <link rel="stylesheet" type="text/css" href="MyStyle.css">
        <script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
        <script type="text/javascript" src="MyJS.js"></script>
    </head>
    <body>
        <p id="p">Try hovering over me!<br>
        An extra line<br>
        so it's easier<br>
        to hover...</p>
    </body>
</html>

Nothing special there. Now for our JavaScript:

$(function () {
    $('#p').hover(function () {
        $(this).addClass('hovering');
    }, function () {
        $(this).removeClass('hovering');
    });
});

So we get out p element and then call the hover function which takes two functions as input. One function is called when your mouse enters the paragraph and the other function is called when your mouse leaves the paragraph (moving your icon over an element is called hovering). Now in this function we call the jQuery function and pass it this. The this keyword is a little difficult in JavaScript. This is the context in which you are currently operating, so this can refer to the window object (the ‘general context’), to an object in which you are currently operating, or in this case the HTML element on which the hover event is fired. So when we pass the p element (this) to the jQuery function we get a jQuery object on which we can call jQuery functions, such as text or addClass and removeClass. So we’re dynamically adding classes. But since our CSS applies a certain style to those classes we now get dynamic styling on our page!

jQuery UI

I want to show another quick example of how powerful JavaScript, and jQuery in particular, really is. For this we’re going to need jQuery UI. Another library that’s made by the jQuery people and uses jQuery, but adds functionality specifically for your UI (User Interface). Next to a JavaScript file the jQuery UI library makes use of a CSS file too. We can get both from the Google CDN we’ve used earlier. So here is the HTML. It looks large, but it’s quite simple.

<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <title>My first JavaScript!</title>
        <link rel="stylesheet" href="https://ajax.googleapis.com/ajax/libs/jqueryui/1.11.3/themes/smoothness/jquery-ui.css" />
        <script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
        <script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jqueryui/1.11.3/jquery-ui.min.js"></script>
        <script type="text/javascript" src="MyJS.js"></script>
    </head>
    <body>
        <div id="accordion">
            <h3>Page 1</h3>
            <div>
                <p>Some content...</p>
            </div>
            <h3>Page 2</h3>
            <div>
                <p>More content...</p>
            </div>
            <h3>Page 3</h3>
            <div>
                <p>Lots of content...</p>
            </div>
        </div>
        <br>
        <div id="tabs">
            <ul>
                <li><a href="#page1">Page 1</a></li>
                <li><a href="#page2">Page 2</a></li>
                <li><a href="#page3">Page 3</a></li>
            </ul>
            <div id="page1">
                <p>Some content...</p>
            </div>
            <div id="page2">
                <p>More content...</p>
            </div>
            <div id="page3">
                <p>Lots of content...</p>
            </div>
        </div>
    </body>
</html>

And now for some amazingly difficult JavaScript…

$(function () {
    $('#accordion').accordion();
    $('#tabs').tabs();
});

So check out the result with and without those two lines of JavaScript. You’ll be amazed! And that’s the power of JavaScript.

So in this post we’ve become familiar with JavaScript and jQuery. You can build amazing websites using JavaScript. There are literally thousands of JavaScript (and CSS) libraries and frameworks. Some, like jQuery, are pretty all-round, but some are really specific about doing one particular thing. In a later blog post I’ll point out some of the more popular ones.
Try to play around a bit with JavaScript. We’ve only scratched the surface. I haven’t even mentioned prototype, which is vital in fully understanding JavaScript. You can start getting your JavaScript skills up to date with a free ebook from SyncFusion: JavaScript Succinctly. Now as luck would have it there’s also a free jQuery ebook from SyncFusion: jQuery Succinctly. So I recommend creating a free account and downloading these sweet free resources (and no, I’m not affiliated with SyncFusion, I just like the Succinctly series).

JavaScript also adds functionality to get data from or send data to our server without having to refresh our entire page. This technology, called AJAX, is what I will talk about in my next blog post.

Stay tuned!