学习链接

网道教程：Promise

网道教程：对象的扩展

Promise.any

AggregateError 构造函数

AggregateError(errors[, message])

• errors：数组，它的每个成员都是一个错误对象。该参数是必须的。
• message：字符串，表示 AggregateError 抛出时的提示信息。该参数是可选的。

AggregateError 的实例对象有三个属性。

• name：错误名称，默认为“AggregateError”。
• message：错误的提示信息。
• errors：数组，每个成员都是一个错误对象。

Promise.myAny = promiseArr => {
    return new Promise((resolve, reject) => {
        if (!promiseArr[Symbol.iterator]) {
            throw new TypeError(`${promiseArr}is not iterable`);
        }
        if (!Array.isArray(promiseArr)) {
            promiseArr = Array.from(promiseArr);
        }
        const result = [];
        let count = 0;
        promiseArr.forEach((p, i) => {
            Promise.resolve(p).then(
                value => {
                    resolve(value);
                },
                reason => {
                    count++;
                    result[i] = reason;
                    if (count === promiseArr.length) {
                        reject(new AggregateError(result, 'All Promises were rejected'));
                    }
                }
            )
        });
    })
}

测试

iterator 相关测试案例见这里

const resolved = Promise.resolve(42);
const rejected = Promise.reject(-1);
const alsoRejected = Promise.reject(Infinity);
Promise.any([resolved, rejected, alsoRejected])
.then((result) => console.log(result)); // 42
Promise.any([rejected, alsoRejected])
.catch( reason => {
    console.log(reason); // AggregateError: All promises were rejected
    console.log(reason.name); // AggregateError
    console.log(reason.message); // All promises were rejected
    console.log(reason.errors); // [-1, Infinity]
});
Promise.myAny([resolved, rejected, alsoRejected])
.then((result) => console.log(result));
Promise.myAny([rejected, alsoRejected])
.catch( reason => {
    console.log(reason);
    console.log(reason.name);
    console.log(reason.message);
    console.log(reason.errors);
});