About Nicholas C. Zakas

Recent Posts

Timed array processing in JavaScript

Not too long ago, I blogged about a way to asynchronously process JavaScript arrays to avoid locking up the browser (and further, to avoid displaying the long-running script dialog). The chunk() function referenced in that original blog post is as follows: function chunk(array, process, context){ var items = array.concat(); //clone the array setTimeout(function(){ var item... […]

Computer science in JavaScript: Credit card number validation

Credit cards on the web sites have become just about as ubiquitous as sign-in forms. One of my favorite moments in computer science was learning the algorithm for determining a valid credit card number. The process doesn’t involve making a call to a server or checking accompanying information, just a basic algorithm that uses a... […]

The best way to load external JavaScript

Not too long ago, I wrote about loading JavaScript without blocking by creating a dynamic <script> tag. When <script> tags are in the flow of an HTML document, the browser must stop rendering and wait for the script file to download and execute before continuing (example). Creating a new <script> tag via JavaScript avoids this... […]

Safari doesn’t properly display one-bit favicons

With my current workload, most of my debugging involves JavaScript and, sometimes, CSS. This is the first time I can remember needing to actively debug an image. I saw an issue where a favicon wasn’t being displayed properly in Safari (both 3 and 4). I kept going back and forth between browsers, verifying that the... […]

Introduction to sessionStorage

One of the most interesting parts of the recent browser evolution has been the explosive growth in the number of options for client-side data storage. Prior to this past year, our only viable cross-browser method of storing data on the client was cookies. Cookies have the downside of adding additional overhead to server requests and... […]

Common debugging mistakes

When web developers think about debugging, they typically think about tools such as Firebug that are used to figure out the crazy CSS and JavaScript issues we encounter every day. Tools can be useful for debugging but debugging is more about a way of solving problems than any particular tool. As such, good debugging approaches... […]

Firefox 3.5/Firebug XMLHttpRequest and readystatechange bug

Last Thursday I was debugging an issue at work that was reported by two colleagues using Firefox 3.5. Initially, they had neglected to mention their fast upgrade to the latest Firefox and I spent some time fruitlessly trying to reproduce the issue. The complaint was that our page wasn’t displaying an Ajax response even though... […]

JavaScript minification/compression and performance

Last week, I came across a blog post by Matt Snider of Mint.com in which he was talking about ways to improve the output of YUI Compressor on JavaScript code. This led me to dig up a presentation I gave last year at Yahoo!’s internal Front End Engineering Summit entitled Extreme JavaScript Compression with YUI... […]

Event delegation in JavaScript

Last week, I spoke at and attended the Velocity web performance conference in San Jose. It was a lot of fun and I learned a lot in the other sessions I sat in on. During one session, Steve Souders announced to everyone that I had covered event delegation in my chapter from his new book,... […]

Loading JavaScript without blocking

I was reading Steve Souder’s blog post on loading scripts without blocking in which he notes that dynamically creating a <script> element and assigning its src attribute leads to a download that doesn’t block other downloads or page processes. His post is missing an example of how to do this, so I thought I’d pick... […]