//Pormise function MyPromise (executor) {
        var self = this     self.status = 'pending'     self.resolveValue = null     self.rejectValue = null     self.resolveCallbackList = []  //用来存储resolve的回调函数     self.rejectCallbackList = []  //用来存储reject的回调函数     function resolve (value) {
            if (self.status === 'pending') {
                self.status = 'Fulfilled'             self.resolveValue = value             self.resolveCallbackList.forEach(function (item) {
                    item()             })         }     }     function reject (value) {
            if(self.status === 'pending') {
                self.status = 'Rejected'             self.rejectValue = value             self.rejectCallbackList.forEach(function (item) {
                    item()             })         }     }     try {
            executor(resolve, reject)     } catch (e) {
            reject(e)     } }     function resultIsPromise (nextValue, res, rej) {
            if(nextValue instanceof MyPromise) {
                nextValue.then(function (val) {
                    res(val)             }, function(reason) {
                    rej(reason)             })         } else {
                res(nextValue)         }     }     MyPromise.prototype.then = function (resolve, reject) {
            if (!resolve) {
                 resolve = function(val) {
                    return val             }         }         if (!reject) {
                 reject = function (val) {
                    throw new Error(val)             }         }         var self = this         var nextPromise = new MyPromise(function(res, rej) {
                    setTimeout(function() {
                        if (self.status === 'Fulfilled') {
                        try{
                            // var newResolveVal = resolve(self.resolveValue)                         // res(newResolveVal)                         var newResolveVal = resolve(self.resolveValue)                         resultIsPromise(newResolveVal, res, rej)                     } catch(e) {
                            rej(e)                         }                     }                 }, 0)                 setTimeout(function () {
                        if (self.status === 'Rejected') {
                        try{
                            var newRejectVal = reject(self.rejectValue)                         resultIsPromise(newRejectVal, res, rej)                     } catch(e) {
                            rej(e)                     }                     }                 }, 0)             if (self.status === 'pending') {
                    if(typeof resolve === 'function') {
                        self.resolveCallbackList.push(function () {
                            setTimeout(function() {
                                try{
                                    var newResolveVal = resolve(self.resolveValue)                                 resultIsPromise(newResolveVal, res, rej)                             } catch (e) {
                                    rej(e)                             }                         })                     })                 }                 if(typeof reject === 'function') {
                        setTimeout(function () {
                            self.rejectCallbackList.push(function () {
                                try{
                                    var newRejectVal = reject(self.rejectValue)                                 resultIsPromise(newRejectVal, res, rej)                             } catch(e) {
                                  rej(e)                             }                         })                     }, 0)                 }             }         })         return nextPromise } //race

MyPromise.race = function (promises) {
      return new MyPromise(function (res, rej) {
          promises.forEach( function (item) {
              item.then(res, rej)       })   }) }

MyPromise.resolve = function (val) {
        return new MyPromise(function (resolve) {
            resolve(val)     }) } MyPromise.catch = function (val) {
        return new MyPromise(function (undefined,reject) {
            reject(val)     }) } MyPromise.all = function (promises) {
        return new MyPromise(function(resolve, reject){
        var countNum=0;     var promiseNum=promises.length;     var resolvedValue=[];     for(var i=0;i