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| const PENDING = 'pending'
const RESOLVED = 'resolved'
const REJECTED = 'rejected'
const asyncFun = (fn) => {
setTimeout(fn, 0)
}
class Promise_ {
status;
resolver;
rejecter;
constructor(executor, options) {
this.status = PENDING;
executor(res => {
asyncFun(() => {
this.status = RESOLVED;
this.resolver?.(res);
});
}, err => {
asyncFun(() => {
this.status = REJECTED;
this.rejecter?.(err);
asyncFun(() => {
throw Error(err);
})
})
})
}
then(resolver, rejecter) {
this.resolver = resolver;
this.rejecter = rejecter;
}
static reject(err) {
return new Promise_((resolve, reject) => {
reject(err);
})
}
static resolve(value) {
if(value instanceof Promise_) return value;
return new Promise_((resolve) => {
resolve(value);
})
}
static all(promisers) {
return new Promise_((resolve, reject) => {
let count = 0;
const resArr = [];
const resolver = (res, index) => {
resArr[index] = res;
count++;
if(count === promisers.length) {
resolve(resArr);
}
};
const rejecter = (err) => {
reject(err)
};
promisers.map((promiser, index) => {
promiser.then(
res => resolver(res, index),
err => rejecter(err)
);
})
})
}
static race(promisers) {
return new Promise_((resolve, reject) => {
let flag = false;
const resolver = res => {
if(!flag) {
flag = true;
resolve(res);
};
};
const rejecter = err => {
reject(err)
};
promisers.map(promiser => {
promiser.then(
resolver,
rejecter
);
})
})
}
static any(promisers) {
return new Promise_((resolve, reject) => {
let stopReject = false;
const resolver = res => {
if(!stopReject) {
stopReject = true;
resolve(res);
};
};
const errs = [];
let count = 0;
const rejecter = err => {
if(stopReject) return;
count++;
errs.push(err);
if(count === promisers.length) {
reject(errs);
asyncFun(() => {
throw new AggregateError(errs)
});
}
};
promisers.map(promiser => {
promiser.then(
resolver,
rejecter
);
})
})
}
}
const promise1 = new Promise_((resolve, reject) => {
setTimeout(() => {
resolve(1)
}, 100)
})
const promise2 = new Promise_((resolve, reject) => {
setTimeout(() => {
resolve(2)
}, 50)
})
const promise3 = new Promise_((resolve, reject) => {
setTimeout(() => {
resolve(3)
}, 0)
})
Promise_.race([promise1, promise2, promise3]).then(res => {
console.log(res);
}, err => {
console.log(err);
})
const promise4 = Promise_.resolve(promise3);
promise4.then(res => {
console.log(res);
})
const promise5 = Promise_.reject(new Error('fail'));
promise5.then(
() => {},
(err) => {
console.log(err);
}
);
console.log(5);
|
