Working on one of the Chromebooks Google lets you borrow on Virgin America flights, I noticed scrolling down the page on my airbnb.com dashboard was much slower than on my normal laptop. I chalked it up to weak Chromebook hardware, but other sites were scrolling just fine. box-shadow had caused slow scrolling on our search results page before, so I did some investigation.I used Chrome's Timeline tab to see the duration of paint events on the page. Before each test I forced a garbage collection and scrolled to the same window position using window.scroll(0, 140). Then I clicked the down arrow i...

In Firefox 8, we’ve added support for insertAdjacentHTML(). It’s an ancient feature of Internet Explorer that has recently been formalized in HTML5 and then spun out into the DOM Parsing specification. The bad news is that Firefox is the last major browser to implement this feature. The good news is that since other major browsers implement it already, you can start using it unconditionally as soon as the Firefox 8 update has been rolled out to users.Basic UsageinsertAdjacentHTML(position, markup) is a method on HTMLElementDOM nodes. It takes tw...

Many sites on the web are good. They are well-designed, clear, have great information architecture and are easy to navigate. Often, web designers emphasize the “design” part too much, and neglect the other equally important things. However, there are sites which aren’t that aesthetically pleasing, but still are the best sites in the world. They may look like a big, sad bag of wrestling underwear on the outside, but their underlying user experience is really, really refined, and thus makes the appearance part fade away while visiting the site. How and why?A case study: �...

The request validation feature in ASP.NET provides a certain level of default protection against cross-site scripting (XSS) attacks. In previous versions of ASP.NET, request validation was enabled by default. However, it applied only to ASP.NET pages (.aspx files and their class files) and only when those pages were executing.In ASP.NET 4, by default, request validation is enabled for all requests, because it is enabled before the BeginRequest phase of an HTTP request. As a result, request validation applies to requests for all ASP.NET resources, not just .aspx page requests. This includes req...

A small company called AppMobi is enabling developers to create HTML5 apps that tap into native hardware and OS capabilities of mobile devices, such as gravity sensing, accelerometer, GPS, camera, sound and vibration, and the file system, InfoWorld reports. 'Its MobiUs browser for iOS implements HTML5's DirectCanvas API for gaming, as well as the HTML5 local storage API for saving executables and data in the browser cache so that apps can run offline. But what makes MobiUs more than just yet another browser is the set of libraries AppMobi provides app developers to access native hardware ...

This post is about JavaScript performance but I would like to start it by telling a story that might seem unrelated to JS. Please bear with me if you don’t like C.A story of a C programmer writing JavaScriptMr. C. is a C programmer as you can probably guess from his name. Today he was asked by his boss to write a very simple function: given an array of numbered 2d points calculate vector sum of all even numbered points... He opens his favorite text editor and quickly types something like (I’ll be intentionally skipping some #include boilerplate):typedef s...

One of the problems I encountered when I started programming ASP.NET websites was to do with the Request.QueryString function. The first projects I was worked on were built with VB.NET and I used the following code to check the existence of a query string variable:VB.NET Codeview plaincopy to clipboardprint?If Request.QueryString("[VARIABLE]") <> Nothing Then        'CODE HERE  End If  This code checked if the variable existed and if it was populated.Moving to C# I automatically assumed that the&nbs...

Well, that was a veritable shitstorm (sorry for the language).  Long story short, MelonCard was featured today on TechCrunch (along with other500Startups companies, also on VentureBeat, Forbes, …) and everything broke all at once.  Every. little. thing.  We had rolled out a huge change to MelonCard over the last few days to make our site a seamless “everything just updates” look-good / feel-good product using NodeJS long-polling with a slick KnockoutJS dynamic jQuery Templates front end.  We did our du...