Auto insert JS on file upload

how geocities or tripod working...

[lonelyani]

Hey folks,
I just wanted to know how geocities or tripod insert javascript automatically when u upload a page there?

For instance, you take a free hosting from tripod and put some pages there. While cheking them on browser, you'll see some ads on your page which is generated dynamically or a pop-up window.

Any idea how its done?

Cheers,
Ani.

[lonelyani]

BUMP!
Any one?

[adni18]

I know Geocities uses script tags, which can unlawfully be cancelled out, of course (not that I'm encouraging that). The scripts are added when the server creates and outputs the page.

[rocknbil]

If I had to guess, I would say it's probably a server-side cron job that goes through all the pages in their server to insert the ads into user pages. So when you upload the page, their programming edits it.