Title: Service Workers
Published: July 15, 2026
Last modified: July 16, 2026
---
# Service Workers
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[A Service Worker](https://developer.mozilla.org/en-US/docs/Web/API/Service_Worker_API/Using_Service_Workers)
is used to handle the HTTP traffic using the in-browser [`PHPRequestHandler`](https://developer.wordpress.org/playground/developers/architecture/browser-concepts).
Imagine your PHP script renders the following page [in the iframe viewport](https://developer.wordpress.org/playground/developers/architecture/browser-iframe-rendering):
```html
John's Website
Homepage
Blog
Contact
```
When the user clicks, say the `Blog` link, the browser would normally send a HTTP
request to the remote server to fetch the `/blog` page and then display it instead
of the current iframe contents. However, our app isn’t running on the remote server.
The browser would just display a 404 page.
Enter [Service Workers](https://developer.mozilla.org/en-US/docs/Web/API/Service_Worker_API/Using_Service_Workers)–
a tool to intercept the HTTP requests and handle them inside the browser:
### Service Worker setup
The main application living in `/index.html` is responsible for registering the
service worker.
Here’s the minimal setup:
**/app.js:**
```javascript
function main() {
await registerServiceWorker(
phpClient,
"default", // PHP instance scope
"/sw.js", // Must point to a valid Service Worker implementation.
"1" // Service worker version, used for reloading the script.
);
}
```
You will also need a separate `/service-worker.js` file that actually intercepts
and routes the HTTP requests. Here’s what a minimal implementation looks like:
**/service-worker.js**:
```javascript
// Intercepts all HTTP traffic on the current domain and
// passes it to the Worker Thread.
initializeServiceWorker();
```
First published
July 15, 2026
Last updated
July 16, 2026
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Changelog
[ See list of changes: Service Workers ](https://developer.wordpress.org/playground/developers/architecture/browser-service-workers/?output_format=md#)
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