Using POST to Send Form Data to a Servlet

Ajax is a great way to make your pages more dynamic. When using ajax, it's common to send data to your servlet in url-encoded form using a GET request. But there can actually be issues with sending information in GET requests. It's generally better practice to send data as a POST request, but there's one subtle detail required to make it work.

msxml3.dll: The system cannot locate the resource specified

I recently started getting this error in my Ajax application:

msxml3.dll: The system cannot locate the resource specified

How to do a while-sleep loop in Javascript

There is no sleep() function in Javascript. It makes sense, really, because Javascript is single threaded. So, a sleep would freeze the entire browser until it returned. But, being able to sleep before continuing processing is a very common need when programming.

The example that comes immediately to mind is polling. When polling a resource, one would naturally do so in a while loop, exiting when the conditions are right for processing to continue.

But how can this be done in Javascript gracefully if there is no way to sleep? You could poll without a sleep, but that would consume all of the browser's processing cycles, effectively locking it up, which is probably not what you would want. Well, here is how to simulate a while-sleep loop in Javascript.

Cannot define a function with window.eval() in IE 7

Sometimes it's useful to evaluate a string in Javascript. There a variety of reasons why one would want to do that, and it's reasonable to expect that the code would be evaluated in the same way as the code in your .js files. I needed to evaluate some code using the window.eval function in Javascript. It worked fine, until I got an error when the evaluated string tried to define a function.

How to Get the CURRENT Style of an Element in Firefox

I was trying to write some Javascript to get some style information about an HTML element. My instinct was to get the element object and access its 'style' property. But this only seemed to work some of the time, which was particularly frustrating! Eventually, I figured it out...

How 'closures' work in Javascript (and Perl)

When I was learning Perl, the concept of a "closure" was one of the more difficult for me. And the first time around, I didn't really get it. So, I put it aside for later and didn't really use them. It then promptly fell to the bottom of the pile and slipped through the cracks. I later started writing a lot of Javascript and re-encountered closures. This time, I was determined to understand what they are and how they work.