Detect .txt in e_URL

[Internetwiz]

Hi all!
What I am trying to do is,
When the user clicks on a link to a .txt file, stop navigation and copy the url to the clipboard.
My method will be to check e_URL to see if it ends in.txt On Navigate. If .txt is detected, stop navigation and copy to clipboard.

Any idea how to check e_URL for '.txt' in filename.txt?

[Internetwiz]

(We can't edit our own posts?)
ADDING: The ideal code would just search the string