abort-controller-x
Version:
Abortable async function helpers
78 lines • 2.77 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
exports.race = void 0;
const AbortError_1 = require("./AbortError");
/**
* Abortable version of `Promise.race`.
*
* Creates new inner `AbortSignal` and passes it to `executor`. That signal is
* aborted when `signal` is aborted or any of the promises returned from
* `executor` are fulfilled or rejected.
*
* Returns a promise that fulfills or rejects when any of the promises returned
* from `executor` are fulfilled or rejected, and rejects with `AbortError` when
* `signal` is aborted.
*
* The promises returned from `executor` must be abortable, i.e. once
* `innerSignal` is aborted, they must reject with `AbortError` either
* immediately, or after doing any async cleanup.
*
* Example:
*
* const result = await race(signal, signal => [
* delay(signal, 1000).then(() => ({status: 'timeout'})),
* makeRequest(signal, params).then(value => ({status: 'success', value})),
* ]);
*
* if (result.status === 'timeout') {
* // request timed out
* } else {
* const response = result.value;
* }
*/
function race(signal, executor) {
return new Promise((resolve, reject) => {
if (signal.aborted) {
reject(new AbortError_1.AbortError());
return;
}
const innerAbortController = new AbortController();
const promises = executor(innerAbortController.signal);
const abortListener = () => {
innerAbortController.abort();
};
signal.addEventListener('abort', abortListener);
let settledCount = 0;
function settled(result) {
innerAbortController.abort();
settledCount += 1;
if (settledCount === promises.length) {
signal.removeEventListener('abort', abortListener);
if (result.status === 'fulfilled') {
resolve(result.value);
}
else {
reject(result.reason);
}
}
}
let result;
for (const promise of promises) {
promise.then(value => {
if (result == null) {
result = { status: 'fulfilled', value };
}
settled(result);
}, reason => {
if (result == null ||
(!(0, AbortError_1.isAbortError)(reason) &&
(result.status === 'fulfilled' || (0, AbortError_1.isAbortError)(result.reason)))) {
result = { status: 'rejected', reason };
}
settled(result);
});
}
});
}
exports.race = race;
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