This post gives you a short JavaScript function to detect your iPad users. Without any further ado, a javascript code to detect iPad users:

function isiPad(){
    return (navigator.platform.indexOf("iPad") != -1);
}

You can also detect browser version and some other stuff by parsing user agent string. Here is an iPad Safari’s user agent string for your reference:

Mozilla/5.0 (iPad; U; CPU OS 3_2 like Mac OS X; en-us) AppleWebKit/531.21.10 (KHTML, like Gecko) Version/4.0.4 Mobile/7B334b Safari/531.21.10

Recently a friend of mine got himself an iPad and I couldn’t not notice how his internet browsing device preferences are changing (PC & iPad). More and more people are using hand held devices namely iPad to browse the internet. So it’s about time to show your iPad visitors some love and display your website designed specifically for iPad.

Let’s see how to do this. There are two way:

1. Redirect iPad visitors
2. Apply different CSS file for iPad users

Most of the posts on the internet related to iPad user detection are suggesting and showing you how to redirect (including myself in my previous iPhone & iPod detection post). However, I would recommend the second option, applying different CSS file.

You can apply the same technique described in applying different styling for javascript enabled browser with CSS post and apply different CSS rules for iPad visitors.

Sidenote: If you decide to redirect iPad users rather than apply different CSS style rules, than I would recommend using server side detection and redirection. You can see an example PHP code by David Walsh.

Hello everyone. I’ve been busy lately with some projects and could not write much on “jQuery HowTo” blog. So, when I came across this little problem, I thought I would share it with you.

Anyway, I was working on one of my projects and I needed to set a background image using jQuery on some div. At first my background setting code looked like this:

$('#myDiv').css('background-image', 'my_image.jpg');
// OR
$('#myDiv').css('background', 'path/to/image.jpg');

But to my surprise it didn’t do the trick. My div’s had no background images. FireBug showed no CSS background properties set and I could not see why background images were not being set by jQuery. Anyway, after 10-20 minutes I realized that jQuery sets CSS properties as key : value and in our case valued had to be in url(image.jpg) form.

Solution to “background images are not being set” problem is to set them like this:

$('#myDiv').css('background-image', 'url(my_image.jpg)');
// OR
$('#myDiv').css('background', 'url(path/to/image.jpg)');

This post is somehow a continuation of our previous post on replacing images, but this post is one step closer to creating an image gallery using jQuery. In this post I will show you how to replace one image with another one in specific time intervals. For example: replacing image1.jpg with image2.jpg every 5 seconds.

In javascript, whenever one says “every X seconds” or “time intervals” s/he is talking about javascript’s setInterval() function and this post is no exception.

So, before we continue, we need to define where our images are coming from. Images URLs can be stored in javascript array or we could choose more elegant way and simply read them from HTML document.

Imagine we have this HTML markup:

<div id="myGallery">
  <img src="image1.jpg" class="active" />
  <img src="image2.jpg" />
  <img src="image3.jpg" />
</div>

We need to hide all images but class="active" one and overlay all of them on one another. Here is a CSS to do that:

#myGallery{
  position:relative;
  width:400px; /* Set your image width */
  height:300px; /* Set your image height */
}
#myGallery img{
  display:none;
  position:absolute;
  top:0;
  left:0;
}
#myGallery img.active{
  display:block;
}

Now, lets write jQuery function that will fade out currently active image and fade in the next image. Here is jQuery code:

function swapImages(){
  var $active = $('#myGallery .active');
  var $next = ($('#myGallery .active').next().length > 0) ? $('#myGallery .active').next() : $('#myGallery img:first');
  $active.fadeOut(function(){
    $active.removeClass('active');
    $next.fadeIn().addClass('active');
  });
}

And now all that’s left is to add setInterval() with our function and the time interval we want our image to fade out and fade in.

// Run our swapImages() function every 5secs
setInterval('swapImages()', 5000);

Now we have gallery/slideshow with images changing every 5 seconds. You can easily customize this jQuery script to create your own slideshow.

Here is how your final code should look like:

<html>
<head>
  <script src="jquery.js">
  </script>
  <script>
    function swapImages(){
      var $active = $('#myGallery .active');
      var $next = ($('#myGallery .active').next().length > 0) ? $('#myGallery .active').next() : $('#myGallery img:first');
      $active.fadeOut(function(){
      $active.removeClass('active');
      $next.fadeIn().addClass('active');
      });
    }

    $(document).ready(function(){
      // Run our swapImages() function every 5secs
      setInterval('swapImages()', 5000);
    }
  </script>
  <style>
    #myGallery{
      position:relative;
      width:400px; /* Set your image width */
      height:300px; /* Set your image height */
    }
    #myGallery img{
      display:none;
      position:absolute;
      top:0;
      left:0;
    }
    #myGallery img.active{
      display:block;
    }
  </style>
</head>
<body>
  <div id="myGallery">
    <img src="image1.jpg" class="active" />
    <img src="image2.jpg" />
    <img src="image3.jpg" />
  </div>
</body>
</html>

The code above is simplified.

This is a simple yet very useful and powerful technique. Using different CSS rules in JavaScript or jQuery enabled browsers lets you customize your website style for JS enabled and disabled browsers using only CSS. Thus you separate concerns of styling and business logic into CSS and javascript. This lets you concentrate on your goals and not styling in your javascript code for example.

All you need to do is to add some class or id to body element using javascript/jquery to specify that javascript/jQuery is available. Then define two rules in you CSS files for js enable and disabled browsers.

Here is an example for Javascript enabled browser:

document.getElementsByTagName("body")[0].setAttribute("class", "js");

And in your CSS file:

.someClass{
    display:block;
}
.js .someClass{
    display:none;
}

Why do I need to have a different CSS styles for jQuery/javascript enabled browser you might ask. Consider you have a drop-down menu on your website’s sidebar and you would like to use jQuery/Javascript to make it drop down on mouse hover. You don’t want to hide (display:none) all submenus’ by default. That would make your website not accessible if user has disabled Javascript on his/her browsers.

Similar to previous example, we can use difference CSS style for jQuery enabled browsers.

if(jQuery){
    jQuery("body").addClass("jq");
}

And in your CSS file:

.someClass{
    display:block;
}
.jq .someClass{
    display:none;
}

Since writing on this blog I posted two jQuery plugins and I needed to compress my js files. So as jQuery documentation suggests I used YUICompressor. YUICompressor is javascript and CSS file/code compressor written in Java language. So to run one yourself you will need JRE installed on your machine.

Then call this command:

java -jar /path/to/yuicompressor.jar path/to/file.js -o path/to/minimized.file.js

Your file will be compressed and saved to path you specified as the last parameter (in our case minimized.file.js).

Links:

1. Download YUICompressor
2. Download JRE (required to run java applications)
3. Online version of YUICompressor