Library to mock local data requests using Fetch
When developing web applications locally, it is not uncommon to request data from an API. However, the API might not actually exist yet, or we might want to control what the responses are.
Typically, this sort of problem has been solved by either writing a separate mock API service alongside the project (i.e. having a Node service running locally with your application) or creating a development database that replicates staging or production environments. Both of these approaches are heavy and can lead to using incorrect data if schemas are out of sync.
This library aims to allow rapid local development without the dependency of a database or fully implemented APIs.
Assuming your project is using fetch
for HTTP operations:
- Either
npm install data-mocks
oryarn add data-mocks
- Import into your project with
import { injectMocks } from 'data-mocks'
- Create an array of mocks you would like to use (see examples)
- Pass array of mocks to
injectMocks()
- Hooray, all HTTP requests to mocked endpoints will now respond with the mocked data you have specified
import { injectMocks } from 'data-mocks';
const mocks = [{
url: /some-endpoint/,
method: 'GET',
response: { some: 'response' },
responseCode: 200
}, {
url: /some-other-endpoint/,
method: 'POST',
response: { another: 'response' },
responseCode: 200,
delay: 1000
}];
injectMocks(mocks);
fetch('http:https://foo.com/some-endpoint')
.then(response => console.log(response)); // resolves with { some: 'response' }
fetch('http:https://foo.com/some-other-endpoint', { method: 'POST', body: {} })
.then(response => console.log(response)); // resolves with { another: 'response' } after a 1 second delay
In this example, we define two mock responses in our mocks
array. The Mock objects are described by the Mock interface. We then inject the mocks into our application via the injectMocks()
function. Finally, when we use fetch to make a request to endpoints that match our mock objects, the mocked responses are returned (note: the second fetch will respond after the conigured delay in milliseconds).
Property | Type | Required | Description |
---|---|---|---|
url | RegExp | ✅ | Regular expression that matches part of the URL |
method | string | ✅ | HTTP method matching one of 'GET', 'POST', 'PUT', 'DELETE' |
response | any | ✅ | Body of the response |
responseCode | number | ❌ | Response code. Defaults to 200 |
delay | number | ❌ | Delay (in milliseconds) before response is returned. Defaults to 0 |
Parameter | Type | Required | Description |
---|---|---|---|
mocks | Mock[] | ✅ | Injects list of mock responses into application. Any HTTP requests made to matching endpoints will trigger the mock response |