JavaScript Promise.withResolvers API All In One

JavaScript Promise.withResolvers API All In One

Promise.withResolvers()

// 使用解构的方式，更优雅的自动获取内部的  resolve, reject  方法 ✅
const {promise, resolve, reject } = new Promise.withResolvers();

// 等价于, 使用外部变量，手动赋值引用内部 resolve, reject  方法 💩
let resolve, reject;
const promise = new Promise((res, rej) => {resolve = res;reject = rej;
});

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/withResolvers

demos

cancelable Promise / cancel Fetch request

const cancelablePromise = <T>(asyncFn: () => Promise<T>) => {let rejected = false;const { promise, resolve, reject } = Promise.withResolvers<T>();return {run: () => {if (!rejected) {asyncFn().then(resolve, reject);}return promise;},cancel: () => {rejected = true;reject(new Error('CanceledError'));},};
};// test
const sleep = (ms: number) => new Promise(res => setTimeout(res, ms));const demo = cancelablePromise(async () => {await sleep(1000);return 'Hello';
});// IIFE
(async () => {try {const value = await ret.run();console.log('value =', value);} catch (err) {console.log('erroe = ', err);}
})();setTimeout(() => {demo.cancel();
}, 500);

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refs

https://webdeveloper.beehiiv.com/p/cancel-promises-javascript

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