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Documentation Index

Fetch the complete documentation index at: https://docs.getpostchi.com/llms.txt

Use this file to discover all available pages before exploring further.

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.

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File naming

Place a file named <request-name>.before.js in the same folder as your request file: 
requests/
  auth/
    login.chttp
    login.before.js   ← runs before login.chttp
For a script that applies to every request in a folder, create before.js in that folder: 
requests/
  auth/
    before.js         ← runs before every request in auth/ and subfolders
    login.chttp
    refresh.chttp
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.

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Available context

Postchi injects these variables into every before script:
VariableTypeDescription
requestobjectThe request about to be sent. Mutating this object changes what Postchi sends.
envobjectAll active environment variables as string key-value pairs. Read-only.
fetchfunctionThe global fetch function.

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The request object

PropertyTypeDescription
request.methodstringHTTP method, e.g. "GET"
request.urlstringFull URL including any template variables already resolved
request.headersobjectHeaders as { name: value } pairs
request.bodystring | nullRequest body as a string, or null

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Examples

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Add a dynamic header

// Add a timestamp to every request
request.headers['X-Request-Time'] = new Date().toISOString();

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Build the URL from environment variables

// Append a version query parameter from the environment
const version = env.api_version || 'v1';
request.url = request.url + '?version=' + version;

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Modify a JSON body

// Add a nonce to the request body before sending
const body = JSON.parse(request.body);
body.nonce = Math.random().toString(36).slice(2);
request.body = JSON.stringify(body);

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Add a Bearer token from the environment

request.headers['Authorization'] = 'Bearer ' + env.api_token;

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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.