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Configuration

On any fetch-mock instance, set configuration options directly on the fetchMock.config object. e.g.

const fetchMock = require('fetch-mock');
fetchMock.config.sendAsJson = false;

Available options​

Options marked with a † can also be overridden for individual calls to .mock(matcher, response, options) by setting as properties on the options parameter

includeContentLength†​

{Boolean} default: true

Sets a Content-Length header on each response, with the exception of responses whose body is a FormData or ReadableStream instance as these are hard/impossible to calculate up front.

matchPartialBody​

{Boolean} default: false

Match calls that only partially match a specified body json. Uses the is-subset library under the hood, which implements behaviour the same as jest's .objectContaining() method.

allowRelativeUrls​

{Boolean} default: false

fetch in node.js does not support relative urls. For the purposes of testing browser modules in node.js it is possible to use this flag to avoid errors. However, you may prefer to use jsdom or similar to set globalThis.location to an instance of the DOM class Location.

Custom fetch implementations​

fetch, Headers, Request, Response can all be set on the configuration object, allowing fetch-mock to mock any implementation of fetch, e.g. node-fetch. e.g.

import { default as fetch, Headers, Request, Response } from 'node-fetch';

import fetchMock from 'fetch-mock';

fetchMock.config = Object.assign(fetchMock.config, {
	Request,
	Response,
	Headers,
	fetch,
});