ReadableByteStreamController: error() method
Baseline
2026
Newly available
Since March 2026, this feature works across the latest devices and browser versions. This feature might not work in older devices or browsers.
Note: This feature is available in Web Workers.
The error() method of the ReadableByteStreamController interface causes any future interactions with the associated stream to error with the specified reason.
This is commonly called by an underlying source to surface an error from the interface where it gets its data (such as a file-read or socket error). It can also be called from elsewhere to trigger a stream error, for example if another part of the system that the stream relies on fails.
Syntax
error(errorObject)
Parameters
errorObject-
Any object that you want future interactions to fail with.
Return value
None (undefined).
Exceptions
TypeError-
Thrown if the source object is not a
ReadableByteStreamController, or the stream is not readable for some other reason.
Examples
The example in Using readable byte streams > Creating a readable socket push byte stream shows how you might use error() to manually trigger a stream error if another part of the system it relies on fails.
Specifically, the underlying source start() method calls readRepeatedly() to perform all setup operations and to make a request for data.
This returns a promise.
If there are any errors thrown when reading the data they will be caught by the chained catch() function.
In catch() we then call error() on the controller, passing the reason from the underlying source.
function start(controller) {
readRepeatedly().catch((e) => controller.error(e));
}
function readRepeatedly() {
return socket.select2().then(() => {
// …
});
}
Specifications
| Specification |
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| Streams # ref-for-rbs-controller-error① |
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