All posts tagged ‘wiki’

File Under: Ajax

Ajax for Beginners

JavaScript has had the XMLHttpRequest object for almost a decade now, but it really only started getting wide attention in 2004. All this attention was mostly due to some showoff web applications that made every developer who saw them think, “I want my site to do that!” But it also has to do with the spiffy, spiffy name given to it by the folks at AdaptivePath, who named this asynchronized application Ajax. Maybe you’ve heard of it?

A few high-profile Google applications in particular made a splash with Ajax: Maps and Gmail were first. It also powers some of the core functionality in the user interface of the ever-so-popular photo sharing site Flickr. By now, Ajax has become integral to the fabric of the web, especially in the era of real-time applications like Twitter, Buzz and Wave (all of which use Ajax extensively in their webapp front ends, for the record). Ajax may also lay claim to being the first JavaScript object with its own fan website. doesn’t count, although I did have a scintillating chat with a lady there once about the getTimeZoneoffset method.

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File Under: Glossary

Data Binding

As a computer science term, data binding is the substitution of a real value in a program after it has been compiled.

For example, during compilation a compiler can assign symbolic addresses to certain variables or instructions. When the program is bound, or linked, the binder replaces the symbolic addresses with real machine addresses. The moment at which binding occurs is called “bind time” or “link time.” In dHTML, data binding allows the client to look into a database and retrieve the content. This data can be automatically displayed in your table using the HTML data binding extensions, or you can manipulate the data with a script.

File Under: Glossary

Index Color

Producing images for the web invariably means minimizing the number of colors (and therefore the file size), and the index color system is another step in this squishing process. With a 216-color palette loaded, Photoshop will map an image to those colors when you move it into index color mode. While this helps the compression and allows you to choose bit depth, it also makes the colors dither, or shift numerically, to the palette. One way to compensate for dithering in the index mode is to use a histogram, which is basically a bar graph of each color’s frequency in the image. In most image-processing programs, you can manipulate the histogram and determine how much weight to give certain colors in the resulting palette.

File Under: Glossary


Many image-processing programs, like Adobe Photoshop, allow you to build images in layers. These layers are created one at a time and placed on top of each other to assemble the whole image. While the file is a pile of little layered images, you can manipulate each layer individually and look at how each change will alter the completed picture.

File Under: Glossary

Referral Network

Think of the food court at the mall. Most of the time, mallsters will go there looking for food in general, then decide what to eat after they’ve checked out the selection. The eaters benefit because they don’t have to wander all over the mall looking for lunch, and the feeders benefit from the added exposure. A referral network works in the same way. The web is perfect for this kind of marketing, since sites with similar audiences can be grouped just by linking them together. has an incredibly successful network of thousands of mini-bookstores. The small bookstores get more customers, and Amazon gets money for the books they sell to the little guys – a perfect symbiotic relationship.