@tapico/msw-webarchive
A utility to drive requests handlers through a .har
web-archive file for the
Mock Service Worker library. This utility allows you to mock server
handlers by using .har
web-archive file which can be created by using applications like Charles,
ProxyMan or the Chrome Developer Tools.
Why you use this?
We have been using it during the development of web-applications, while the backend API endpoints
weren't available yet or when we want to reproduce a problem of a customer. This way we can request
the customer to send us a .har web-archive file and let this file drive the network requests to our
back-end, this has greatly eased reproducing problems reported.
Getting started
To use this library you need to have a HAR (*.har
) file generated from the network traffic of your
application. Follow the instructions below to learn how to do that.
Install
npm install @tapico/msw-webarchive --save-dev
Install Mock Service Worker
Follow the Installation instructions from the Mock Service Worker documentation.
Create a HAR file
Chrome

- Open the DevTools in Chrome (Option + Command + I /
Shift + CTRL + J).
- Go to the "Network" tab in the DevTools.
- Click on the downward-facing arrow icon to "Export HAR".
- Save the HAR archive on your disk.
Firefox

- Open the DevTools in Firefox (Option + Command + I /
Shift + CTRL + I).
- Go to the "Network" tab in the DevTools.
- Click on the cog icon on the left of the top bar.
- Click "Save All As HAR" option in the dropdown menu.
- Save the HAR archive on your disk.
Generate request handlers
import { setupWorker } from 'msw'
import { setRequestHandlersByWebarchive } from '@tapico/msw-webarchive'
import * as traffic from './example.har'
const worker = setupWorker()
setRequestHandlersByWebarchive(worker, traffic)
worker.start()
Options
quiet: boolean
Disables the logging of debugging messages of the library.
setRequestHandlersByWebarchive(worker, har, {
quiet: true,
})
strictQueryString: boolean
Stricly match a request URL query parameters during request URL matching. When set to false
,
request URL query parameters are ignored during matching.
setRequestHandlersByWebarchive(worker, har, {
strictQueryString: false,
})
resolveCrossOrigins: (origin: string) => string
Override the Access-Control-Allow-Origin
response header whenever it's present.
setRequestHandlersByWebarchive(worker, har, {
resolveCrossOrigins(origin) {
return '*'
},
})
domainMappings: Record<string, string>
Allow mapping the domains in your har file to something else. This may be useful if you are making
relative requests against the origin (eg. fetch('/hello')
), you may want to use a domainMapping
configuration like:
setRequestHandlersByWebarchive(worker, har, {
domainMappings: {
'http://example.com': 'http://localhost',
},
})