A simple solution could be the contains block to check, if the url contains the string
http://localhost:8000/post/
For more advanced solutions you can try one of the regex extensions
- Matches Regex Extension by luv.ak.tech
- RegEx Extension by Appsbeheerder
- Xreg Regex Extension by danielmistura, PCRE regular expressions for App
taken from the extensions directory App Inventor Extensions | Pura Vida Apps
Taifun