The clever bit about JSIO is the placeholder URLs – i.e. the “jsio.gif#…” that goes in your image src attributes and background-image CSS properties. Everything after the “#” is the filename of the image that should be displayed. It doesn’t have to be the filename at all, it could just be a single letter or number or symbol or whatever. It doesn’t matter to JSIO. To JSIO, everything after the “#” is just a key into the resources object that holds data uri encoded images. As long as the key is unique (which it will be if you use filenames, since no two files in the same directory can have the same name), JSIO is happy.

Using filenames as keys into our resources object is beneficial to humans. Much more beneficial than coordinates in a sprite, simply because (hopefully) the filenames are meaningful; they describe the image. In comparison to sprites, the JSIO resources object also makes maintaining your image data much easier as it is trivial to add or remove images without having to move other images around within the sprite (and consequently all coordinates referencing your moved image).

Another benefit of using filenames as keys into the JSIO resources object is for fallback. If JSIO detects your browser is IE7 or lower, it’ll strip out “jsio.gif#” leaving just your image key as the image src, which is hopefully a valid URL to the original image. Also, if JSIO detects you’re running IE8 and the image data is larger than 32KB it’ll do the same thing*.

* …but not yet in v1.0.0 alpha

Since the image key is after the “#” (it is the URL “fragment”), your browser won’t send multiple requests for the 1*1px jsio.gif file – it’ll just send one request, cache the response, and use it again. By the way, the jsio.gif image is just a transparent 1*1px gif (for maximum efficiency), but it could be an “spinner” image or something, which is shown temporarily whilst the JSIO resources file is downloaded.

This post is about JSIO – JSIO is a tiny library that allows you to make fewer requests to your server by packaging all your site image data in a JavaScript file in data uri format. The official site for JSIO can be found here: jsio.freestyle-developments.co.uk. You can read more about why I started this project here.

Migrating WordPress to a new URL

WordPress is a nonsense, and stores it’s URL in multiple places in the database. If you want to move your WordPress install to a different host, exec the following MySQL commands to change the URL in all instances:

UPDATE wp_options 
   SET option_value = REPLACE(option_value, "[Old site URL]", "[New site URL]")
 WHERE option_value LIKE "%[Old site URL]%";
 UPDATE wp_posts 
   SET post_content = REPLACE(post_content, "[Old site URL]", "[New site URL]")
 WHERE post_content LIKE "%[Old site URL]%";
  UPDATE wp_posts 
   SET guid = REPLACE(guid, "[Old site URL]", "[New site URL]")
 WHERE guid LIKE "%[Old site URL]%";

   UPDATE wp_postmeta
   SET meta_value = REPLACE(meta_value, "[Old site URL]", "[New site URL]")
 WHERE meta_value LIKE "%[Old site URL]%";

Replace [Old site URL] and [New site URL] appropriately

Use this form to generate the SQL for YOUR database