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Pre-request scripts

A pre-request script runs before the request is sent — it is the first step of the send pipeline. It can:

  • read and modify the request method, URL, body, and headers (fp.request.*);
  • read and write environment variables (fp.environment.get/set), which are persisted after the send;
  • stash ephemeral values for the post-response phase (fp.variables.get/set);
  • emit logs (fp.log/warn/error); and
  • define tests (fp.test).
fp.environment.set('token', 'abc');
fp.request.headers.set('Authorization', `Bearer ${fp.environment.get('token')}`);

Scripts run inside an isolated, synchronous sandbox with a single global, fp. See the execution model for the full API and its constraints.

The sandbox guards against accidental footguns, but it is not designed to contain a malicious script. Treat a .http file from an untrusted source the way you would treat a shell script from the same source: read it before running it.