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| function Promise(executor) { let self = this self.status = 'pending' self.value = null self.onResolveCallbacks = [] self.onRejectCallbacks = []
function resolve(value) { if (self.status === 'pending') { self.status = 'fulfilled' self.value = value self.onResolveCallbacks.forEach(cb => cb(self.value)) } }
function reject(reason) { if (self.status === 'pending') { self.status = 'rejected' self.value = reason self.onRejectCallbacks.forEach(cb => cb(self.value)) } }
try { executor(resolve, reject) } catch (e) { reject(e) } }
Promise.prototype.then = function(onFulfilled, onRejected) { let self = this onFulfilled = typeof onFulfilled === 'function' ? onFulfilled : v => v onRejected = typeof onRejected === 'function' ? onRejected : r => { throw r } let returnedPromise = null if (self.status === 'pending') { return returnedPromise = new Promise((resolve, reject) => { self.onResolveCallbacks.push(() => { setTimeout(() => { try { let x = onFulfilled(self.value) ResolutionProcedure(returnedPromise, x, resolve, reject) } catch (e) { reject(e) } }, 0) }) self.onRejectCallbacks.push(() => { setTimeout(() => { try { let x = onRejected(self.value) ResolutionProcedure(returnedPromise, x, resolve, reject) } catch (e) { reject(e) } }, 0) }) }) } else if (self.status === 'fulfilled') { return returnedPromise = new Promise((resolve, reject) => { setTimeout(() => { try { let x = onFulfilled(self.value) ResolutionProcedure(returnedPromise, x, resolve, reject) } catch (e) { reject(e) } }, 0) }) } else if (self.status === 'rejected') { return returnedPromise = new Promise((resolve, reject) => { setTimeout(() => { try { let x = onRejected(self.value) ResolutionProcedure(returnedPromise, x, resolve, reject) } catch (e) { reject(e) } }, 0) }) } }
Promise.prototype.catch = function(onRejected) { return this.then(null, onRejected) }
Promise.prototype.race = function(values) { return new Promise(function(resolve, reject) { for (let i = 0, len = values.length; i < len; i++) { values[i].then(resolve, reject) } }) }
Promise.all = function(promises) { return new Promise(function(resolve, reject) { let resolvedCounter = 0 let promiseNum = promises.length let resolvedValues = new Array(promiseNum) for (let i = 0; i < promiseNum; i++) { (function(i) { Promise.resolve(promises[i]).then(function(value) { resolvedCounter++ resolvedValues[i] = value if (resolvedCounter === promiseNum) { return resolve(resolvedValues) } }, function(reason) { return reject(reason) }) })(i) } }) }
Promise.prototype.finally = function(callback) { let constructor = this.constructor return this.then( function(value) { return constructor.resolve(callback()).then(function() { return value }) }, function(reason) { return constructor.resolve(callback()).then(function() { return constructor.reject(reason) }) } ) }
function ResolutionProcedure(promise, x, resolvePromise, rejectPromise) { try { if (promise === x) { return rejectPromise(new TypeError('2.3.1')) } if (x instanceof Promise) x.then(((value) => { ResolutionProcedure(promise, value, reslove, reject) }, (reason) => { reject(reason) })) let called = false if (x !== null && (typeof x === 'object' || typeof x === 'function')) { try { let then = x.then if (typeof then === 'function') { then.call(x, (value) => { if (called) return called = true return ResolutionProcedure(promise, value, resolvePromise, rejectPromise) }, (reason) => { if (called) return called = true return rejectPromise(reason) }) } else { return resolvePromise(x) } } catch (e) { if (called) return called = true return rejectPromise(e) } } else { return resolvePromise(x) } } catch (e) { return rejectPromise(e) } }
Promise.deferred = function() { let defer = {} defer.promise = new Promise((resolve, reject) => { defer.resolve = resolve defer.reject = reject }) return defer }
module.exports = Promise
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