手写简单的promise

function Promise(fn) {
                var that = this;
                this.status = "pedding";
                this.value = undefined; // 成功返回值
                this.reason = undefined; // 失败返回值
                this.onFulfilledArr = []; // 保存成功回调函数
                this.onRejectedArr = []; // 保存失败的回调函数

                // 成功
                function resolve(value) {
                    if (that.status === "pedding") {
                        that.value = value;
                        // 依次执行回调函数
                        that.onFulfilledArr.forEach(fn => {
                            return fn(value);
                        });
                        that.status = "fulfilled";
                    }
                }
                // 失败
                function reject(reason) {
                    if (that.status === "pedding") {
                        that.reason = reason;
                        that.onRejectedArr.forEach(fn => {
                            return fn(season);
                        });
                        that.status = "rejected";
                    }
                }
                //
                fn(resolve, reject);
            }
            Promise.prototype.then = function(onFulfilled, onRejected) {
                // return new Promise(function(resolve, reject) {
                //     console.log(resolve);
                // });
                if (this.status === "pedding") {
                    if (typeof onFulfilled === "function") {
                        this.onFulfilledArr.push(onFulfilled);
                    }
                }
                if (this.status === "pedding") {
                    if (typeof onRejected === "function") {
                        this.onRejectedArr.push(onRejected);
                    }
                }
            };
            var t = new Promise(function(resolve, reject) {
                setTimeout(() => {
                    resolve(2);
                }, 500);
            });
            t.then(data => {
                console.log(data);
            });

暂未实现then的链式调用