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Route handlers

Routes definitions can be:

  • JSON to return as application/json
  • a string to return as text/plain
  • a function: (request, h, proxy) => Promise<response>

    • request is the request information, which can be edited

    • method - the HTTP request method

    • url - the requested url, parsed into object form, including query string parsing
    • headers - object containing the request headers
    • payload - for PUT and POST, contains the payload in JSON format if applicable
    • textPayload - for PUT and POST, contains the payload in string format
    • rawPayload - for PUT and POST, contains the payload in Buffer format

    • h is the hapi response toolkit, if you need to construct your own responses

    • proxy is a function which returns a promise of the response from the target. If any of the properties of the request are altered before calling this method, the changes are used to make the request.

    The return value of the function can be any one of the following:

    • A JavaScript object. This will be returned as an application/json response
    • A response created from h.response(...) (see hapi response builder)
    • The (optionally altered) response object from calling proxy() (the third argument to the route function)
    • A promise that resolves to any of the above values

Examples of modifying requests🔗

Change the HTTP method🔗

Set req.method to whichever method you need to proxy to.

import { ProxyConfig } from 'intervene';

const config: ProxyConfig = {
  target: '',

  routes: {
    // Change `POST /api/cats` to `PUT /api/cats` and forward to the server
    'POST /api/cats': (req, h, proxy) => {
      req.method = 'PUT'
      return proxy();

export default config;

Change URL properties🔗

req.url is the parsed URL of the target. This means you can update the host, path or anything else to update where the request will be proxied to.

Properties to edit:

  • host: the hostname (without port)
  • port: the port to use (if not default for the protocol, otherwise null)
  • protocol: the protocol to use, followed by :. e.g. http: or https:
  • pathname: the path (without the query)
  • query: the parsed query string as an object
import { ProxyConfig } from 'intervene';

const config: ProxyConfig = {
  target: '',

  routes: {
    '/api/cats': (req, h, proxy) => {
      // Change `GET /api/cats` to `GET /api/v2/cats`
      req.url.pathname = '/api/v2/cats';

      // update the query property, to add `?api_version=2`
      req.url.query.api_version = '2';
      return proxy();

export default config;

Response object🔗

The response object is returned from calls to proxy() and also calls to httpRequest contains the following properties

  • body: A JavaScript object with the parsed JSON response (if content type is application/json)
  • text: <string | undefined> The response in string format.
  • rawResponse: <Buffer> The response as a raw binary Buffer
  • statusCode: <number> The HTTP status code of the response
  • headers: <Array<string | string[] | undefined>> An object with key value pairs of the header values

A route handler can return the response object directly, or modify it and return it. Setting text or rawResponse properties will override the response body - whichever is set last takes precedence.