const PENDING = 'pending';
const FULFILLED = 'fulfilled';
const REJECTED = 'rejected';
const MYPROMISESTATE = '[[MypromiseState]]';
const MYPROMISEVALUE = '[[MypromiseResult]]';
let Mypromise = (function () {
function Mypromise(fn) {
Object.defineProperty(this, MYPROMISESTATE, {
value: PENDING,
enumerable: false,
writable: true
})
Object.defineProperty(this, MYPROMISEVALUE, {
value: undefined,
enumerable: false,
writable: true
})
Object.defineProperty(this, 'onFulfilledList', {
value: [],
enumerable: false,
writable: true
})
Object.defineProperty(this, 'onRejectedList', {
value: [],
enumerable: false,
writable: true
})
if (typeof fn === 'function') {
fn(Mypromise.resolve.bind(this), Mypromise.reject.bind(this))
} else {
throw new Error('is not a function')
}
}
Object.defineProperty(Mypromise.prototype, 'catch', {
value: function (errfn) {
if (this[MYPROMISESTATE] === REJECTED) {
let errValue = errfn(this[MYPROMISEVALUE])
if (errValue !== undefined) {
return new Mypromise((resolve, reject) => {
reject(errValue)
})
}
} else if (this[MYPROMISESTATE] === PENDING) {
if (typeof errfn === 'function') this.onRejectedList.push(errfn);
return this
}
},
enumerable: false,
writable: true
})
Object.defineProperty(Mypromise.prototype, 'then', {
value: function (fn, errfn) {
if (this[MYPROMISESTATE] === FULFILLED) {
let getValue = fn(this[MYPROMISEVALUE])
if (getValue !== undefined) {
if (getValue.then !== undefined) return getValue
return new Mypromise((resolve, reject) => {
resolve(getValue)
})
} else {
return new Mypromise((resolve, reject) => {
resolve()
})
}
} else if (this[MYPROMISESTATE] === REJECTED) {
if (errfn !== undefined) {
errfn(this[MYPROMISEVALUE])
} else {
return new Mypromise((resolve, reject) => {
reject(this[MYPROMISEVALUE])
})
}
} else if (this[MYPROMISESTATE] === PENDING) {
if (typeof fn === 'function') this.onFulfilledList .push(fn);
if (typeof errfn === 'function') this.onRejectedList .push(errfn);
return this
}
},
enumerable: false,
writable: true
})
Object.defineProperty(Mypromise.prototype, 'finally', {
value: function (fn) {
if (this[MYPROMISESTATE] !== PENDING) {
fn()
}
},
enumerable: false,
writable: true
})
Object.defineProperty(Mypromise, 'resolve', {
value: function (value) {
if (this instanceof Mypromise) {
if (this[MYPROMISESTATE] === PENDING) {
this[MYPROMISESTATE] = FULFILLED;
this[MYPROMISEVALUE] = value;
if (this.onFulfilledList.length !== 0) this.onFulfilledList.forEach(fn => fn(value))
return this
}
} else {
return new Mypromise(resolve => void resolve(value))
}
},
enumerable: false,
writable: true
})
Object.defineProperty(Mypromise, 'reject', {
value: function (value) {
if (this instanceof Mypromise) {
if (this[MYPROMISESTATE] === PENDING) {
this[MYPROMISESTATE] = REJECTED;
this[MYPROMISEVALUE] = value;
if (this.onRejectedList.length !== 0) this.onRejectedList.forEach(errfn => errfn(value))
return this
}
} else {
return new Mypromise((resolve, reject) => {
reject(value)
})
}
},
enumerable: false,
writable: true
})
Object.defineProperty(Mypromise, 'all', {
value: function (value) {
if (!Array.isArray(value)) throw new Error('is not a Array')
let mypromiseData = [];
let mypromiseArr = Array.from(value);
let index = 0;
return new Mypromise((resolve, reject) => {
for (let i in mypromiseArr) {
mypromiseArr[i].then(res => {
mypromiseData[i] = res;
if (++index === mypromiseArr.length) resolve(mypromiseData)
}).catch(err => {
reject(err)
})
}
})
},
enumerable: false,
writable: true
})
Object.defineProperty(Mypromise, 'race', {
value: function (value) {
if (!Array.isArray(value)) throw new Error('is not a Array')
let mypromiseData = [];
let mypromiseArr = Array.from(value);
let index = 0;
return new Mypromise((resolve, reject) => {
for (let i in mypromiseArr) {
mypromiseArr[i].then(res => {
resolve(res)
}).catch(err => {
reject(err)
})
}
})
},
enumerable: false,
writable: true
})
Object.defineProperty(Mypromise.prototype, Symbol.toStringTag, {
value: 'Mypromise',
enumerable: false,
writable: true
})
return Mypromise
})()
