RequestMock.onRequestTo().respond Method

Specifies the mock response.

requestMock.onRequestTo().respond([body] [, statusCode] [, headers]) → this
Parameter Type Description Default
body (optional) Object | String | Function | Buffer A mocked response body. Pass an object for a JSON response, a string for an HTML response or a function to build a custom response. An empty HTML page is returned with the response.
statusCode (optional) Number The response status code. 200
headers (optional) Object Custom headers added to the response in the property-value form. The content-type header. If the header is not provided, it is set depending on the body parameter’s type. If body is an object, the content-type header is set to application/json. If body has another type, the content-type header is set to text/html; charset=utf-8.
const mock = RequestMock()
    .respond({ data: 123 }) // a JSON response
    .respond('<html></html>') // an HTML response
    .respond(null, 204) // an empty response with a status code
    .respond('<html_markup>', 200, { // a response with custom headers
        'server': 'nginx/1.10.3',
    .respond(Buffer.from([0x62, 0x75, 0x66, 0x66, 0x65, 0x72])) // a response with binary data
    .respond((req, res) => { // a custom response
        res.headers['x-calculated-header'] = 'calculated-value';
        res.statusCode                     = '200';

        const parsedUrl = url.parse(req.url, true);

        res.setBody('calculated body ' + parsedUrl.query['param']);

A Custom Response Function

const templateMock = RequestMock()
    .respond((req, res) => {
        // ...

A custom response function takes two parameters.

Parameter Type Description
req RequestOptions A request to be mocked.
res Object A mocked response.

Use information provided by the req parameter about the request to configure the response using the res parameter.

The res exposes the following members:

Property Type Description
headers Object The response headers.
statusCode Number The response status code.
Method Description
setBody(value) Sets the response body. Accepts a string as a parameter.

The response function can be synchronous or asynchronous:

const mock = RequestMock()
    .respond((req, res) => {
        res.setBody('<html><body><h1>This is a page</h1></body></html>');
    .respond(async (req, res) => {
        const data = await promisifiedHttpsGet('');

        res.headers['access-control-allow-origin'] = '*';


The RequestOptions object contains the request parameters.

Property Type Description
headers Object The request headers in the property-value form.
body Buffer The request body.
url String The URL to which the request is sent.
protocol String The protocol to use. Default: http:.
hostname String The alias for the host.
host String The domain name or IP address of the server to issue the request to. Default: localhost.
port Number The port of the remote server. Default: 80.
path String The request path. Should include query string if any. E.G. ‘/index.html?page=12’. An exception is thrown when the request path contains illegal characters. Currently, only spaces are rejected but that may change in the future. Default: ‘/‘.
method String The string specifying the HTTP request method. Default: ‘GET’.
credentials Object Credentials to use for Windows (NTLM) or Basic authentication. HTTP Basic authentication requires a username and a password. NTLM authentication services may need to know your workstation and domain. See HTTP Authentication.
proxy Object If a proxy is used, the property contains information about its host, hostname, port, proxyAuth, authHeader and bypassRules.