Response: error() static method
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since October 2017.
Note: This feature is available in Web Workers.
The error() static method of the Response interface returns a new Response object associated with a network error.
This is mainly useful when writing service workers: it enables a service worker to send a response from a fetch event handler that will cause the fetch() call in the main app code to reject the promise.
An error response has its type set to error.
Syntax
Response.error()
Parameters
None.
Return value
A Response object.
Examples
Returning a network error from a service worker
Suppose a web app has a service worker, which contains the following fetch event handler:
// service-worker.js
self.addEventListener("fetch", (event) => {
const url = new URL(event.request.url);
if (url.pathname === "/salamander.jpg") {
event.respondWith(Response.error());
}
});
With this service worker, all fetch requests from the app will pass through the service worker to the network, except for requests to fetch "salamander.jpg", which will reject. This means that the following main thread code would throw an error, and the catch handler will run.
// main.js
const image = document.querySelector("#image");
try {
const response = await fetch("salamander.jpg");
const blob = await response.blob();
const objectURL = URL.createObjectURL(blob);
image.src = objectURL;
} catch (e) {
console.error(e);
}
Specifications
| Specification |
|---|
| Fetch # ref-for-dom-response-error① |
Browser compatibility
| desktop | mobile | server | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
error() static method
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Legend
Tip: you can click/tap on a cell for more information.
- Full support
- Full support