Before scripts run immediately before Postchi sends a request. You receive the request object and can mutate it freely — whatever state it’s in when the script finishes is what gets sent.
File naming
Place a file named <request-name>.before.js in the same folder as your request file:
For a script that applies to every request in a folder, create before.js in that folder:
The folder-level before.js runs first, then the request-level <name>.before.js. This means the request-level script always sees changes made by the folder-level script.
Available context
Postchi injects these variables into every before script:
The request object
Examples
Build the URL from environment variables
Modify a JSON body
Add a Bearer token from the environment
Notes
Before scripts cannot cancel a request — they can only transform it. If your script throws an error, Postchi surfaces the error and does not send the request.
Put shared authentication logic in a folder-level before.js so you only write it once and it applies to every request in that folder automatically.