javascript / expert
Snippet
Cancellable Async Pipeline Control using AbortSignal inside Svelte Reactive State
Constructs an asynchronous task wrapper utilizing AbortController to automatically abort outdated asynchronous operations when new requests are triggered in Svelte reactive contexts. This prevents race conditions and out-of-order state updates.
snippet.js
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export function createCancellableTask(asyncFn) {let currentController = null;return async (...args) => {if (currentController) {currentController.abort('SUPERSEDE');}currentController = new AbortController();const { signal } = currentController;try {return await asyncFn(signal, ...args);} catch (err) {if (err === 'SUPERSEDE' || signal.aborted) return;throw err;}};}
svelte
Breakdown
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let currentController = null;
Holds a closure reference to the active AbortController instance for cancellation tracking.
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if (currentController) { currentController.abort('SUPERSEDE'); }
Cancels any ongoing async execution before initiating a fresh invocation.
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currentController = new AbortController();
Instantiates a new AbortController to manage the lifecycle of the current execution.
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return await asyncFn(signal, ...args);
Passes the active AbortSignal directly to the target asynchronous handler.
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if (err === 'SUPERSEDE' || signal.aborted) return;
Gracefully suppresses errors resulting specifically from intentional task cancellations.