JavaScript execute asynchronous functions in Parallel with count and Promise All In One
JavaScript 使用 count 和 Promise
并行执行异步函数
errors
function promiseAll<T>(functions: Fn<T>[]): Promise<T[]> {return new Promise((resolve, reject) => {let temp = [];for(let [i, func] of Object.entries(functions)) {console.log(`✅ i =`, i);console.log(`✅ func =`, func);(async (index) => {await func().then(value => {temp[index] = value;console.log(`❓ index =`, index);console.log(`value =`, value);console.log(`temp =`, temp);if(temp.length === functions.length) {return resolve(temp);}// temp = (3) [4, empty, 16] ❌// if(temp.length === functions.length && !temp.some(v => Object.prototype.toString.call(v) === '[object Promise]')) {// return resolve(temp);// }}).catch(err => {return reject(err);});})(i);}});
};function promiseAll<T>(functions: Fn<T>[]): Promise<T[]> {return new Promise((resolve, reject) => {let temp = [];let index = 0;for(let [i, func] of Object.entries(functions)) {console.log(`✅ i =`, i);// console.log(`func =`, func);func().then(value => {// temp[i] = value;temp[index] = value;index += 1;// temp.push(value);console.log(`❓ i =`, i);// index 0 twice bug ❌ 覆盖 bug// 💩 temp = [ 4, <1 empty item>, 16 ]console.log(`value =`, value);console.log(`temp =`, temp);// value = 16// temp = [ 4, <1 empty item>, 16 ] 2// setTimeout 时间先后顺序 bug ❌if(temp.length === functions.length && !temp.some(v => Object.prototype.toString.call(v) === '[object Promise]')) {return resolve(temp);}// setTimeout 时间先后顺序 bug ❌// setTimeout(() => {// if(temp.length === functions.length) {// return resolve(temp);// }// }, 0);}).then(() => {// setTimeout 时间先后顺序 bug ❌// console.log(`temp =`, temp);// if(temp.length === functions.length) {// return resolve(temp);// }}).catch(err => {return reject(err);}).finally(() => {// setTimeout 时间先后顺序 bug ❌// console.log(`temp =`, temp);// if(temp.length === functions.length) {// return resolve(temp);// }});// if(temp.length === functions.length) {// return resolve(temp);// }// let id = setInterval(() => {// if(temp.length === functions.length && !temp.some(v => Object.prototype.toString.call(v) === '[object Promise]')) {// clearInterval(id);// return resolve(temp);// }// }, 0);}});
};
function promiseAll() {return new Promise((resolve, reject) => {let temp = [];for(let [i, func] of Object.entries(functions)) {// console.log(`i =`, i);// console.log(`func =`, func);func().then(value => {console.log(`value =`, value);temp[i] = value;console.log(`temp =`, temp, i);}).catch(err => {return reject(err);});}// ❌ bugconsole.log(`temp ? =`, temp);setTimeout(() => {console.log(`temp =`, temp);if(temp.length === functions.length) {return resolve(temp);}}, 0);});
};solutions
type Fn<T> = () => Promise<T>function promiseAll<T>(functions: Fn<T>[]): Promise<T[]> {return new Promise((resolve, reject) => {let temp = [];let count = 0;for(let [i, func] of Object.entries(functions)) {func().then(value => {temp[i] = value;count += 1;// count ✅// 使用 count 避免出现 empty 返回值情况 ✅if(count === functions.length) {return resolve(temp);}}).catch(err => reject(err));}});
};
demos
LeetCode 2721. Execute Asynchronous Functions in Parallel
function promiseAll() {return new Promise((resolve, reject) => {let temp = [];let count = 0;for(let [i, func] of Object.entries(functions)) {func().then(value => {temp[i] = value;count += 1;// count ✅// 使用 count 避免出现 empty 返回值情况 ✅if(count === functions.length) {return resolve(temp);}}).catch(err => reject(err));}});
};const functions = [() => new Promise(resolve => setTimeout(() => resolve(4), 50)), () => new Promise(resolve => setTimeout(() => resolve(10), 150)), () => new Promise(resolve => setTimeout(() => resolve(16), 100))];promiseAll(functions).then(console.log);
https://leetcode.com/problems/execute-asynchronous-functions-in-parallel/description/?envType=study-plan-v2&envId=30-days-of-javascript
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