第二周作业：完成简易promise

.vscode/launch.json

@@ -0,0 +1,23 @@
+{
+  // 使用 IntelliSense 了解相关属性。 
+  // 悬停以查看现有属性的描述。
+  // 欲了解更多信息，请访问: https://go.microsoft.com/fwlink/?linkid=830387
+  "version": "0.2.0",
+  "configurations": [
+    {
+      "type": "node",
+      "request": "launch",
+      "name": "Egg Debug",
+      "runtimeExecutable": "npm",
+      "runtimeArgs": [
+        "run",
+        "test",
+        "--",
+        "--inspect-brk"
+      ],
+      "console": "integratedTerminal",
+      "restart": true,
+      "autoAttachChildProcesses": true
+    },
+  ]
+}

index.js

@@ -8,34 +8,83 @@ function myPromise(constructor) {
   self.reason = undefined;//定义状态为rejected的时候的状态
 
   function resolve(value) {
-
-    // TODO resolve如何改变状态及返回结果
-
+    self.value = value
+    if(self.status !== 'pending'){
+      return
+    }
+    self.status = 'resolve'
+    const { fullfilled } = self
+    if(fullfilled){
+      fullfilled(self.value)
+    }
   }
 
   function reject(reason) {
-
-    // TODO reject如何改变状态及返回结果
+    if(self.status !== 'pending'){
+      return
+    }
+    self.reason = reason
+    self.status = 'reject'
+    // promise的then函数执行时，this值好像是undefined,所以不能直接this.fullfilled
+    const { rejected } = self
+    if(rejected){
+      rejected(reason)
+    }
 
   }
 
   //捕获构造异常
 
   try {
-
     constructor(resolve, reject);
-
   } catch (e) {
-
     reject(e);
-
   }
 
 }
 
 myPromise.prototype.then = function (onFullfilled, onRejected) {
-
-  //TODO then如何实现
-
+  const { status, value, reason} = this
+  if(!onFullfilled ||  typeof onFullfilled !== 'function') {
+    throw new Error('参数异常，最少需要传入完成函数')
+  }
+  // 已完成状态直接执行完成函数，并且返回新的已完成状态的promise,数据更新为完成函数的返回值
+  if(status == 'resolve'){
+    let result = value
+    if(onFullfilled && typeof onFullfilled == 'function') {
+      // 这里可以trycatch，给出合理错误提示
+      result = onFullfilled(value)         
+    }
+    return new myPromise(function(resolve){ resolve(result)})
+  } else if(status == 'reject'){
+    // 错误状态直接执行错误函数，并且返回新的错误状态的promise,使用同一个错误对象
+    if(onRejected && typeof onRejected == 'function') {
+      onRejected(reason)   
+    }
+    return new myPromise(function(_resolve,reject){ reject(reason)})
+  } else {
+    const self = this
+    // 进行中状态，依然需要返回新的promise对象
+    // 感觉两个promise对象耦合了，不过目前没有更好的思路
+    return new myPromise(function(resolve,reject){
+      self.fullfilled = function(value){
+        let result = value 
+        // 看别人的作业，想起来这里报错了下个promise要进入reject状态
+        try {
+          result = onFullfilled(value)
+          resolve(result)
+        } catch (error) {
+          reject(error)
+        }
+      }
+      self.rejected = function(reason){
+        if(onRejected && typeof onRejected == 'function') {
+          onRejected(reason)     
+        }
+        reject(reason)
+      }
+    })
+  }
 }
+
 module.exports = myPromise

index.test.js

@@ -1,9 +1,103 @@
 const myPromise = require('./index');
 
-var p = new myPromise(function (resolve, reject) { resolve('isOk') });
+const p1 = new myPromise(function (resolve, reject) { resolve('isOk') });
 test('测试primose的then是否成功', () => {
   expect.assertions(1);
-  return p.then(data => {
+  p1.then(data => {
     expect(data).toBe('isOk');
   });
-});
+});
+
+
+test('测试异步primose的then是否成功', async () => {
+  expect.assertions(1);
+  const p2 = new myPromise(function (resolve, reject) { 
+    setTimeout(()=> 
+      resolve('isOk')
+    , 1000)
+  });
+  await p2.then(data => {
+    expect(data).toBe('isOk');
+  });
+});
+
+
+test('测试primose的then函数的错误函数入参', () => {
+  expect.assertions(1);
+  const p3 = new myPromise(function (_resolve, reject) { 
+    reject('isno')
+  });
+  p3.then(data => {
+    expect(data).toBe('isOk');
+  }, err => {
+    expect(err).toBe('isno');
+  });
+});
+
+const p4 = new myPromise(function (_resolve, reject) { 
+  setTimeout(()=> reject('isno'), 1000)
+});
+test('测试异步primose的then函数的错误函数入参', () => {
+  expect.assertions(1);
+  p4.then(data => {
+    expect(data).toBe('isOk');
+  }, err => {
+    expect(err).toBe('isno');
+  });
+});
+
+const p5 = new myPromise(function (resolve, reject) { resolve('isOk') });
+test('测试primose的连续then是否成功', () => {
+  expect.assertions(2);
+  p5.then(data => {
+    expect(data).toBe('isOk');
+    return 'isOk'
+  }).then(data => {
+    expect(data).toBe('isOk');
+  });
+});
+
+const p6 = new myPromise(function (resolve, reject) { 
+  setTimeout(()=> resolve('isOk'), 1000)
+});
+test('测试异步primose的连续then是否成功', () => {
+  expect.assertions(2);
+  p6.then(data => {
+    expect(data).toBe('isOk');
+    return 'isOk'
+  }).then(data => {
+    expect(data).toBe('isOk');
+  });
+});
+
+const p7 = new myPromise(function (_resolve, reject) { 
+  reject('isno')
+});
+test('测试primose的连续then函数的错误函数入参', () => {
+  expect.assertions(2);
+  p7.then(data => {
+    expect(data).toBe('isOk');
+  },err => {
+    expect(err).toBe('isno');
+  }).then(data => {
+    expect(data).toBe('isOk');
+  },err => {
+    expect(err).toBe('isno');
+  });
+});
+
+const p8 = new myPromise(function (_resolve, reject) { 
+  setTimeout(()=> reject('isno'), 1000)
+});
+test('测试异步primose的连续then函数的错误函数入参', () => {
+  expect.assertions(2);
+  p8.then(data => {
+    expect(data).toBe('isOk');
+  },err => {
+    expect(err).toBe('isno');
+  }).then(data => {
+    expect(data).toBe('isOk');
+  },err => {
+    expect(err).toBe('isno');
+  });
+});

yarn-error.log

@@ -0,0 +1,40 @@
+Arguments: 
+  D:\Program Files\nodejs\node.exe C:\Users\cxs\AppData\Roaming\npm\node_modules\yarn\bin\yarn.js install
+
+PATH: 
+  C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Windows\System32\OpenSSH\;D:\Git\cmd;D:\Python27;D:\Program Files\nodejs;C:\Users\cxs\AppData\Local\Microsoft\WindowsApps;;D:\VSCode\bin;C:\Users\cxs\AppData\Local\Pandoc\;C:\Users\cxs\AppData\Roaming\npm
+
+Yarn version: 
+  1.22.18
+
+Node version: 
+  16.15.0
+
+Platform: 
+  win32 x64
+
+Trace: 
+  Error: connect ETIMEDOUT 192.168.252.160:4873
+      at TCPConnectWrap.afterConnect [as oncomplete] (node:net:1187:16)
+
+npm manifest: 
+  {
+    "name": "homework8",
+    "version": "1.0.0",
+    "description": "",
+    "main": "index.js",
+    "scripts": {
+      "test": "jest"
+    },
+    "author": "ccpro",
+    "license": "MIT",
+    "devDependencies": {
+      "jest": "^28.1.3"
+    }
+  }
+
+yarn manifest: 
+  No manifest
+
+Lockfile: 
+  No lockfile