陈卓在9月8日提交了week13的周报

陈卓/week13/promise.js

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+class Promise{
+  //构造函数
+  constructor(executor) {
+    this.PromiseState = 'pending'
+    this.PromiseResult = null
+    this.callbacks = []
+    const self = this
+    function resolve(data) {
+      if (self.PromiseState !== 'pending') return;
+      //修改对象的状态（PromiseState）
+      self.PromiseState = 'resolved'
+      //设置对象结果值（PromiseResult）
+      self.PromiseResult = data
+      setTimeout(() => {
+        self.callbacks.forEach(item => {
+          item.onResolved()
+        })
+      })
+    }
+    function reject(data) {
+      if (self.PromiseState !== 'pending') return;
+      //修改对象的状态（PromiseState）
+      self.PromiseState = 'rejected'
+      //设置对象结果值（PromiseResult）
+      self.PromiseResult = data
+      setTimeout(() => {
+        self.callbacks.forEach(item => {
+          item.onRejected()
+        })
+      })
+    }
+    try {
+      //执行器函数  同步调用
+      executor(resolve, reject)
+
+    } catch (error) {
+      //修改Promise对象状态为失败
+      reject(error)
+    } 
+  }
+
+  //添加then方法
+then (onResolved, onRejected) {
+    const self = this
+    //then方法没有传递第二个参数，设置默认值
+    if (typeof onRejected !== 'function') {
+      onRejected = reason => {
+        throw reason
+      }
+    }
+    if (typeof onResolved !== 'function') {
+      onResolved = value => value
+    }
+    return new Promise((resolve, reject) => {
+      //封装函数
+      function callback(type) {
+        let result = type(self.PromiseResult)
+        try {
+          if (result instanceof Promise) {
+            //如果是Promise类型的对象
+            result.then(v => {
+              resolve(v)
+            }, j => {
+              reject(j)
+            })
+          } else {
+            //结果的对象状态变为成功
+            resolve(result)
+          }
+        } catch (e) {
+          reject(e)
+        }
+      }
+      //调用回调
+      if (this.PromiseState === 'resolved') {
+        setTimeout(() => {
+          callback(onResolved)
+        })
+      }
+      if (this.PromiseState === 'rejected') {
+        setTimeout(() => {
+          callback(onRejected)
+        })
+      }
+
+      //异步任务回调的执行
+      if (this.PromiseState === 'pending') {
+        //保存回调函数
+        this.callbacks.push({
+          onResolved: function () {
+            callback(onResolved)
+          },
+          onRejected: function () {
+            callback(onRejected)
+          },
+        })
+      }
+    })
+  }
+
+//添加catch方法  妙！！！！
+catch (onRejected) {
+    return this.then(undefined, onRejected)
+  }
+
+//添加resolve方法
+static resolve  (value) {
+    return new Promise((resolve, reject) => {
+      if (value instanceof Promise) {
+        value.then(v => {
+          resolve(v)
+        }, j => {
+          reject(j)
+        })
+      } else {
+        resolve(value)
+      }
+    })
+  }
+
+//添加reject方法
+static reject (reason) {
+    return new Promise((resolve, reject) => {
+      reject(reason)
+    })
+  }
+
+//添加all方法   面试常考
+static all (promises) {
+    //返回结果为Promise对象
+    return new Promise((resolve, reject) => {
+      let count = 0
+      let arr = []
+      //遍历
+      for (let i = 0; i < promises.length; i++) {
+        promises[i].then(v => {
+          //此时对象的状态是成功的
+          arr[i] = v
+          count++
+          if (count === promises.length) {
+            resolve(arr)
+          }
+        }, j => {
+          reject(j)
+        })
+
+      }
+    })
+  }
+
+//添加race方法
+static race (promises) {
+    return new Promise((resolve, reject) => {
+      for (let i = 0; i < promises.length; i++) {
+        promises[i].then(v => {
+          resolve(v)
+        }, j => {
+          reject(j)
+        })
+      }
+    })
+  }
+
+}

陈卓/week13/周报.md

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+## 0826 周报
+### 学习笔记/记录
+这周学习了Promise，了解了Promise异步操作的用法，学习了Promise的几种方法
+并且跟着视频教程做了自定义Promise封装，相当于从底层学习了Promise
+
+问题：
+做Promise自定义封装的过程中，由于是分成几天做的，导致刚开始那两天经常突然忘掉Promise的用法
+解决：
+写一个PromiseTest文件，包含各种Promise用法和方法，标明注释，每次忘记就看一遍