Haven't seen that in a while, always a good one!
Yeah, you can invoke the JS parser from any href including the address bar, and just string together code on a single line, delimiting functions with a ;
The main jimmy is using the DOM to get an array of elements (in this case IMG tags), recursing them, and applying some math functions to their coordinate position. The setInterval calls the main function on a defined interval.
Pretty fun stuff - you can swap out the element type to like DIV to munge up all the containers/text, and apply some interesting math functions to plot the X Y positions to things like SIN functions, etc.