Why Does This Xmlhttprequest Fail>?

http://jsfiddle.net/FarqA/ ajax_info.txt is a valid file on my computer. The error returns as thus: Uncaught Error: INVALID_STATE_ERR DOM Exception 11

Solution 1:

Many browsers will refuse to load local files through an XMLHttpRequest as a security measure. AJAX requests are restricted by the Same Origin Policy, but as the linked Wikipedia page notes,

The behavior of same-origin checks and related mechanisms is not well-defined in a number of corner cases, such as for protocols that do not have a clearly defined host name or port associated with their URLs (file:, data:, etc.).

Loading a local file, even with a relative URL, is the same as loading a file with the file: protocol. Many web browsers restrict this, with good reason - imagine running a malicious HTML file on your local machine that could load any file on your computer and post its contents to a remote server.

So my guess is that the problem is that you're trying to load a local file. Try serving your script on a local or remote webserver and see if that fixes the problem. (If you have Python installed, you can go to the directory in question and run python -m SimpleHTTPServer 8000, then go to http://localhost:8000/ in your browser).

Solution 2:

In your script each call too HTTPRequest() is creating a new request object, so the request with the onReadystateChange handler is never getting sent and request that is sent has no handler function. Here's an updated version of your fiddle that should work: http://jsfiddle.net/HwYUS/