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Posted at April 22, 2014 by Nicholas C. Zakas Tags: ECMAScript 6, JavaScript, Proxies This past week I spent an hour debugging an issue that I ultimately tracked down to a silly problem: the property I was referencing didn’t exist on the given object. I had typed request.code and it should have been request.query.code. After sternly lecturing myself for not noticing earlier, a pit formed in my sto

Posted at March 26, 2014 by Nicholas C. Zakas Tags: Books, ECMAScript 6, JavaScript, Writing For almost two years, I’ve been keeping notes on the side about ECMAScript 6 features. Some of those notes have made it into blog posts while others have languished on my hard drive waiting to be used for something. My intent was to compile all of these notes into a book at some point in time, and with the

Posted at February 4, 2014 by Nicholas C. Zakas Tags: JavaScript, Maintainable, Node.js I’ve spent the last few months digging into Node.js, and as usual, I’ve been keeping tabs on patterns and problems that I’ve come across. One problematic pattern that recently came up in a code review was the use of process.exit(). I’ve ended up finding several examples of this, and I’m prepared to go so far as

Posted at December 27, 2013 by Nicholas C. Zakas Tags: Front End Engineers, Interviews There was a really nice article written by Philip Walton last week1 regarding his experience interviewing for front-end engineering roles at various companies in San Francisco. To summarize, he was surprised by the types of questions he was asked (mostly having to do with computer science concepts) and the types

Posted at September 10, 2013 by Nicholas C. Zakas Tags: ECMAScript 6, Functions, JavaScript One of the most interesting new parts of ECMAScript 6 are arrow functions. Arrow functions are, as the name suggests, functions defined with a new syntax that uses an “arrow” (=>) as part of the syntax. However, arrow functions behave differently than traditional JavaScript functions in a number of importan

A long time ago, JSLint was the state of the art in JavaScript linting technology. Then JSHint came along as a fork and took over due to increased flexibility. I welcomed JSHint as my linter of choice and used it everywhere, happily submitting patches and customizing which rules to apply based on the project. At some point I started to feel stifled and frustrated by JSHint as well. There’s no easy

Posted at July 9, 2013 by Nicholas C. Zakas Tags: Performance, process.nextTick, setImmediate, setTimeout One of my favorite new APIs that has been beaten about is setImmediate(). While I’ll concede the naming is completely wrong, the functionality is completely awesome. The basic idea is to tell the browser that you want some JavaScript code executed after the last UI task in the event loop compl

Posted at July 2, 2013 by Nicholas C. Zakas Tags: Internet Explorer, JavaScript, navigator, User Agent String This past week, Microsoft officially unveiled the first preview of Internet Explorer 11 for Windows 8.11. Doing so put to rest a whirlwind of rumors based on leaked versions of the much-maligned web browser. We now know some very important details about Internet Explorer 11, including its

Posted at June 25, 2013 by Nicholas C. Zakas Tags: eval, JavaScript In all of JavaScript, I’m not sure there is a more maligned piece than eval(). This simple function designed to execute a string as JavaScript code has been the more source of more scrutiny and misunderstanding during the course of my career than nearly anything else. The phrase “eval() is evil” is most often attributed to Douglas

Posted at May 21, 2013 by Nicholas C. Zakas Tags: Git, GitHub Recently I asked engineers to share their experiences working with GitHub at companies. I’ve always used GitHub for open source projects, but I was interested in learning more about using it professionally and how one’s development workflow might change given all of GitHub’s capabilities. I set up a gist1 so people could leave the answe

Posted at April 30, 2013 by Nicholas C. Zakas Tags: Blink, Vendor Prefix, Web Development, WebKit When Google announced that it was forking WebKit into Blink, there was a lot of discussion around what this would mean for web developers, and if the WebKit monoculture was truly breaking or not. Amongst the consternation and hypotheticizing was a detail that went overlooked by many: Blink’s plan to s

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 to the containing page. On the other hand, iframes and their associated window ob

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 resolution before I finally offered to write a blog post explaining my view. Along the way, I discover

Internet Explorer 11′s user-agent string: What does it mean? 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 Explo

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 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)

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 makes weakmaps different and useful. A weakmap holds only a weak reference to a key, which m

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

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 be done with media queries on the web. As part of my pondering over the holiday bre

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

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 Explorer 4-6 is heavily responsible for web development as we know it today. A number of pro

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

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. Although sometimes they hit target seemed a little bit too small, I would just

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