CF-Incidents Workers - AbortController and AbortSignal can be created at global scope

[ENF News Bot]

new AbortController(), AbortSignal.abort(), new WritableStream(), and request.signal no longer throw when used during module evaluation (that is, at the top level of your Worker module, outside of a request handler). Previously, these APIs required an active request context and would throw if called at the top level.

// This now works — no error during module startup
const controller = new AbortController();

export default {
	async fetch(request) {
		// The signal can be used across requests
		return new Response("OK", { signal: controller.signal });
	},
};

Signals can also be observed and aborted across different requests, making it easier to coordinate cancellation in long-lived Workers such as Durable Objects.

AbortSignal.timeout() still requires an active request context because it needs to schedule a timer.

For more details, refer to the AbortController documentation.

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