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Posted at April 16, 2013 by Nicholas C. Zakas Tags: iframe, JavaScript, referrer Dealing with iframes is always a double-edged sword. On the one hand, you get sandboxing of content within another page, ensuring that JavaScript and CSS from one page won’t affect another. If the iframe is displayed a page from a different origin then you can also be assured that the page can’t do anything nefarious

Posted at April 1, 2013 by Nicholas C. Zakas Tags: Accessibility, ARIA, HTML, Screen Readers Last week, Pamela Fox tweeted a question to me: @slicknet Do you know the best way to make a that just has an icon accessible? title, aria-label, hidden text? — Pamela Fox (@pamelafox) March 26, 2013 As tends to happen on Twitter, we fruitlessly exchanged 140 character messages trying to get some resolutio

Over the past few days, people have been going a little crazy over the announcement of the Internet Explorer 11 user-agent string. User-agent string announcements are typically met with a keen eye as we are still horribly tied to user-agent sniffing on servers around the world. And so when some beta testers leaked an Internet Explorer 11 user-agent string, people sat up and paid attention. The str

Posted at January 15, 2013 by Nicholas C. Zakas Tags: Accessibility, HTML **Update (15-Jan-2013): ** After a few tweets about this and some re-testing, it appears the issue discussed in this post only affects Internet Explorer and Chrome. The post has been updated to reflect this. If you’ve been doing web development for any amount of time, you have probably come across the recommendation to creat

Posted at December 11, 2012 by Nicholas C. Zakas Tags: ECMAScript 5, JavaScript I was working with a client recently on a project that could make full use of ECMAScript 5 when I came across an interesting problem. The issue stemmed from the use of mixins, a very common pattern in JavaScript where one object is assigned properties (including methods) from another. Most mixin functions look somethin

Posted at November 27, 2012 by Nicholas C. Zakas Tags: Algorithms, Computer Science, JavaScript, Sorting Most discussions about sorting algorithms tend to end up discussing quicksort because of its speed. Formal computer science programs also tend to cover quicksort1 last because of its excellent average complexity of O(n log n) and relative performance improvement over other, less efficient sorti

Posted at November 13, 2012 by Nicholas C. Zakas Tags: Ajax, API, CSS, DOM, JavaScript This week I was scheduled to give a brand new talk at YUIConf entitled, JavaScript APIs you’ve never heard of (and some you have). Unfortunately, a scheduling conflict means that I won’t be able to attend. So instead of letting the work of putting together a brand-= new talk go to waste (or otherwise be delayed)

Posted at November 6, 2012 by Nicholas C. Zakas Tags: ECMAScript 6, JavaScript, WeakMap Weakmaps are similar to regular maps in that they map a value to a unique key. That key can later be used to retrieve the value it identifies. Weakmaps are different because the key must be an object and cannot be a primitive value. This may seem like a strange constraint but it’s actually the core of what make

Like it or not, ECMAScript 6 is going to have classes1. The concept of classes in JavaScript has always been polarizing. There are some who love the classless nature of JavaScript specifically because it is different than other languages. On the other hand, there are those who hate the classless nature of JavaScript because it’s different than other languages. One of the biggest mental hurdles peo

Posted at October 4, 2012 by Nicholas C. Zakas Tags: JavaScript, TypeScript Earlier this week, Microsoft released TypeScript1, a new compile-to-JavaScript language for “application scale JavaScript.” My initial reaction was confusion: Um, why? blogs.msdn.com/b/somasegar/ar… (via @izs) — Nicholas C. Zakas (@slicknet) October 1, 2012 It seems like almost every week there’s a new language that’s tryi

Posted at September 25, 2012 by Nicholas C. Zakas Tags: Arrays, ECMAScript 6, JavaScript, Set For most of JavaScript’s history, there has been only one type of collection represented by the Array type. Arrays are used in JavaScript just like arrays and other languages but pull double and triple duty mimicking queues and stacks as well. Since arrays only use numeric indices, developers had to use o

Posted at January 4, 2012 by Nicholas C. Zakas Tags: CSS, JavaScript, Media Query I’ve been doing a lot of thinking about CSS media queries lately. I’m a big fan of media queries, as I think they bring a sense of sanity to feature detection. That’s a big reason why I was investigating CSS media queries in JavaScript1 and will continue to do so. I think we’re only scraping the surface of what can b

Posted at September 12, 2012 by Nicholas C. Zakas Tags: CSS, CSSLint CSS Lint v0.9.9 is now available both on the command line and at the web site. This release is mostly a maintenance release with a few small features added in. This lays the groundwork for an eventual 1.0.0 release, but that doesn’t preclude the possibility of a 0.9.10 release before then. There’s still a lot of work to do on the

Posted at August 22, 2012 by Nicholas C. Zakas Tags: CSS, DOM, Internet Explorer, JavaScript Long before Internet Explorer became the browser everyone loves to hate, it was the driving force of innovation on the Internet. Sometimes it’s hard to remember all of the good that Internet Explorer did before Internet Explorer 6 became the scourge of web developers everywhere. Believe it or not, Internet

Posted at August 1, 2012 by Nicholas C. Zakas Tags: ECMAScript 6, JavaScript, Quasis Quasi-literals (update: now formally called “template strings”) are a proposed addition to ECMAScript 6 designed to solve a whole host of problems. The proposal seeks to add new syntax that would allow the creation of domain-specific languages (DSLs)1 for working with content in a way that is safer than the soluti

Posted at July 24, 2012 by Nicholas C. Zakas Tags: ECMAScript 6, JavaScript, Syntax I am, just like many in the JavaScript world, watching anxiously as ECMAScript undergoes its next evolution in the form of ECMAScript 6. The anxiety is a product of the past, when we were all waiting for ECMAScript 4 to evolve. The ECMAScript 4 initiative seemed more like changing JavaScript into a completely diffe

Posted at July 5, 2012 by Nicholas C. Zakas Tags: CSS, Hover, iOS, Mobile Recently, I got my first iPad. I’ve had an iPhone since last year, and had gotten used to viewing the mobile specific view of most websites. When I got the iPad, it was my first time experiencing desktop webpages using a touch interface. Generally, the transition was easy. I just tapped on links I wanted to navigate to. Alth

Posted at June 5, 2012 by Nicholas C. Zakas Tags: Blob, File API, JavaScript Up to this point, this series of posts has focused on interacting with files specified by the user and accessed via File objects. The File object is actually a more specific version of a Blob, which represents a chunk of binary data. The size and type properties exist on Blob objects and are inherited by File. In most cas

I’m happy to announce that my latest book, Maintainable JavaScript, is now available in print. Thanks to the folks at O’Reilly, the ebook was released as a preview last month, but now all the edits have been completed and the book is officially done. I’m very excited about this book, even moreso than some of the others, because it’s quite different than any I’ve written before. One of the reasons

Many years ago, I was asked during a job interview at Google what changes I would make to the web in order to provide better experiences. At the top of my list was having some way to work with files other than the <input type="file"> control. Even as the rest of the web was evolving, the way we dealt with files never changed since it was first introduced. Thankfully, with HTML5 and related APIs, w

Posted at April 25, 2012 by Nicholas C. Zakas Tags: JavaScript, localStorage, Performance Now a few weeks removed from a large amount of hand-ringing around the performance of localStorage in browsers, I’ve learned some more about why there was such a concern at Mozilla (which prompted Chris to write his blog post1). The post was met with skepticism because it lacked two key components: numbers an

Posted at March 13, 2012 by Nicholas C. Zakas Tags: JavaScript, Strict Mode ECMAScript 5 introduced strict mode to JavaScript. The intent is to allow developers to opt-in to a “better” version of JavaScript, where some of the most common and egregious errors are handled differently. For a while, I was skeptical, especially with only one browser (Firefox) initially supporting strict mode. Fast forw

Posted at March 7, 2012 by Nicholas C. Zakas Tags: JavaScript, localStorage, Performance Earlier this week, Chris Heilmann wrote a blog post entitled, There is no simple solution for localStorage1 in which he decried localStorage as slow and encouraged everyone to stop using it. Surprisingly, in a post about performance, there was no mention of what “slow” or “terrible performance” actually meant.

Posted at February 22, 2012 by Nicholas C. Zakas Tags: Software Development, Technical Debt In the creation of a web site, there are several groups of people who participate: product managers or marketing representatives who are responsible for defining functionality and design, user interface designers who create the actual visuals, and the developers who are responsible for implementing the fina

Posted at January 19, 2012 by Nicholas C. Zakas Tags: CSS, JavaScript, Media Query In my previous post1, I introduced using CSS media queries in JavaScript both through a custom implementation and using the CSSOM Views matchMedia() method. Media queries are incredibly useful, both in CSS and JavaScript, and so I continued with my research to see how best to take advantage of this capability. As it

I’m very excited to announce that Professional JavaScript for Web Developers, 3rd Edition is now shipping and available in bookstores. Over six years, the first edition was released and it changed my life in ways I never could have anticipated. It was through this book that I ended up at Yahoo! and was invited to speak at conferences for the first time. The first edition was a labor of love and th

Posted at September 19, 2011 by Nicholas C. Zakas Tags: JavaScript, Performance, Timer Those who have attended my talks on JavaScript performance are familiar with my propensity for using setTimeout() to break up long scripts into smaller chunks. When using setTimeout(), you’re changing the time at which certain code is executed, effectively yielding the UI thread to perform the already-queued tas

Posted at September 15, 2011 by Nicholas C. Zakas Tags: ECMAScript, Harmony, JavaScript, Proxy ECMAScript 6, aka “Harmony”, introduces a new type of object called a proxy. Proxies are objects whose default behavior in common situations can be controlled, eliminated, or otherwise changed. This includes definition what happens when the object is used in a for-in look, when its properties are used wi