A timely script

Here's an example of the kind of thing we can do with embedded scripts:

Every time you visit this page, you get an updated report of the time remaining 'til Summer's vacation, but only when the page loads. It's a big number, but even worse: it's not counting down!

Okay, clearly the vacation clock should actually count down, so here's another version:

Reference: http://www.usna.edu/CS/si110/lec/l14/lec.html