cors-bypass
v1.3.7
Published
Bypass the browsers CORS restrictions, without needing to setup a server-side proxy.
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cors-bypass
Bypass the browsers CORS restrictions, without needing to setup a server-side proxy. Demo
- Allows you to make HTTP requests from a HTTPS page
- 100% coverage for the
WebSocketAPI spec
How does this module work?
It uses postMessage to send cross-domain events, which is used to provide mock HTTP APIs (fetch, WebSocket, XMLHTTPRequest etc.). Simplified version
How do I use it
Theres three components to this module: the Server, Adapter and Client.
Server
Simply serve a HTML file on a domain from which you want to make requests from (HTTP domain for example), with the following (use a bundler like Webpack, Parcel etc):
import { Server } from 'cors-bypass'
const server = new Server()<body>
<script src="./node_modules/cors-bypass/lib/server.bundle.js"></script>
</body>Adapter
Next you need a HTML file from the domain that will make requests (your web app's domain). The adapter is in control of forwarding requests from a client located on any page of your site, to the server (using a BroadcastChannel).
import { Adapter } from 'cors-bypass'
const adapter = new Adapter()<body>
<script src="./node_modules/cors-bypass/lib/adapter.bundle.js"></script>
</body>Client
As long as the Adapter is running in a different tab (on the same domain as the client), you will be able to make requests.
// Located somewhere on https://your-site.com
import * as BypassCors from 'cors-bypass'
const client = new BypassCors.Client()
await client.getServer() // null - no server connected yet
await client.openServerInNewTab({
serverUrl: 'http://random-domain.com/server.html',
adapterUrl: 'https://your-site.com/adapter.html'
})
await client.getServer() // { id: 123, url: 'http://random-domain.com/server.html' }
// Create a WebSocket (websocket is loaded in the server tab, but it's API is available on this page)
const ws = new BypassCors.WebSocket('ws://echo.websocket.org')
ws.onopen = () => ws.send('hello')
ws.onmessage = ({ data }) => console.log('received', data)Use cases
HTTP requests for Offline PWAs
As using a Service Worker require HTTPS, it's impossible to connect to local devices which only support HTTP.
Using this module does requires the user to open an extra window, but it lets you bypass cors.