So I’ve been reading the change log for jQuery 1.6 and it’s a doozy, with tons of great improvements (performance particularly) and some nice changes. There’s been a bunch of performance optimizations to both .attr() and .data() functions, which I use often in my projects, so that is definitely welcomed. Not to mention the more clear separation of attributes and properties for DOM elements, which should get rid of some of the weird behaviour I sometimes see with checkboxes and radios buttons when I manipulate their state with JavaScript. On top of that there are improvements to animation performance and a kitchen sink of other changes. Needless to say I’ll be switching my codebase to 1.6 ASAP.
Optimizing JavaScript and jQuery
I’ve been working on a new project — a web application of sorts. Basically, unlike a regular web site, everything in this web applications occurs on the one page. Moreover, due to the nature of the webapp there’s a lot of javascript code handling everything from keyboard input, through DOM updates and to Ajax requests. While not time critical, it is nonetheless essential to keep this webapp working smooth and fast, and so as part of my development work on it I have been delving deeper into the “science” of optimizing javascript code, and also more specifically optimizing jQuery.
I have always been very performance conscious. It probably comes from my work as PC game developer where a single line of non-optimized rendering code could mean the difference between getting 60fps and 20fps during gameplay. In any case, I really enjoyed discovering some new tricks to squeeze more performance out of my code, and admittedly remembering some old ones as well. So I wanted to share some of those tricks, both the basic, but essential ones and the more advanced techniques. Read more »
Better jQuery Placeholder Plugin
A while back I made a post about a simple placeholder script I wrote. The idea was to provide the placeholder functionality that browsers like Chrome and Safari have, to browsers that don’t have it, like Firefox and IE. The script was very simple though and not smart in a few ways, including inability to handle password fields and an incorrect way of checking placeholder support in the browser. Since then I wrote an improved version of the script, in the form of a jQuery plugin. The highlights of this improved script include
- proper use of jQuery’s plugin framework to create a fully chain-able plugin
- support for password fields and text areas
- correct check for placeholder support in browser
- and just overall a better written piece of code
You can see a demo of the plugin in action and download the commented source file (4.7kb), or the minified source file (1.7kb), or the clean (not minified but not commented) source file (2.6kb). Below I’ll go over some of the more interesting parts of script. Read more »
jQuery 1.5 is out
The jQuery team has released a new version of their awesome framework — jQuery 1.5. While not seemingly as significant as the 1.4 release, they made quite a few major changes under the hood.
On top the various bug fixes and performance enhancements one of the major changes in jQuery 1.5 is a complete rewrite of the Ajax module.
Perhaps the largest change is that a call to jQuery.ajax (or jQuery.get, jQuery.post, etc.) now returns a jXHR object that provides consistency to the XMLHttpRequest object across platforms (and allows you to perform previously-impossible tasks like aborting JSONP requests).
Crazy long jQuery animation chains for a slideshow widget
So I was recently coding a slideshow widget using jQuery. Nothing fancy — just a box showing one image, you click an arrow, the next/previous image slides in. The code was also very straightforward — get a handle on the “slides” and use index to loop through them. For one of the animations in the transition (there were labels that were animated separately) I used a simple chain, something like $(slide).find(label).animate(). As I was writing it, it hit me, jQuery has pretty robust chains, they allow mixing pretty much every operation you can do on an element — traversal, manipulation, effects, etc. So I decided to see if I could do the entire slideshow functionality as one long chain (well, technically two, one for each arrow). Here is a demo of the slideshow widget in action. Read more »
Write single-page Ajax web applications with Sammy.js
Tutsplus.com has a great intro tutorial to Sammy.js, a small JavaScript framework that allows you to write single page web apps, similar to Gmail for example. Because Sammy.js is built on top of jQuery it’s very small, only about 20kb. With this framework you can keep track of your app’s state via hash (#) in the URL, without the need to refresh the site as you go from page to page, and of course it allows you to use the browser’s back button as well.
Check out the full tutorial at net.tutsplus.com.
Custom AddThis share button
I wanted to have an AddThis share button that would fit better with the site’s design, and if you’re reading this post on its own page you can scroll down and see what I mean. While AddThis provides plenty of ways to customize their buttons, there is no way to assign your own image to the icon, which means doing it the hard way… well, relatively speaking of course.
There are three main steps to creating a customized share button. There’s some javascript to include in the footer.php, few lines of html to add at the end of your posts, and of course some styles and the icon itself.
Read more »
Simple jQuery placeholder script for input fields
Update: I have created a better version of this script that, among other improvements, supports password fields, unlike the code below.
Placeholder is a very useful attribute of the <input> tag that is specified in the HTML5 spec. It provides a text that goes into the field, by default, and is used as a kind of a quick tip for the user about what they should type into the field, such as “type to search”, or “type in username”. The nice thing about “placeholder”, as oppose to, for example, simply setting some value for the field, is that it automatically disappears when the user starts typing something in, but it reappears if the user ends up leaving the field empty. Unfortunately this attribute, and its functionality, is actually not supported by most browsers, including Firefox 3.6 and IE8, it is however supported by Chrome 4, and possibly Safari 4 though I can’t vouch for the latter.
I recently had a few projects that needed this functionality, and while some of them had email, password and other fields that required validation, one needed just very simple text fields with placeholder text. So I wrote this very simple javascript function, using jQuery, to do just that (I’m using jQuery 1.4.2 here). Read more »