feat:完成作业，tapable2实现

lib/db.js

@@ -1,13 +1,53 @@
-const Tapable = require('tapable')
+const { AsyncSeriesWaterfallHook, AsyncSeriesBailHook } = require("tapable");
 
-class DB extends Tapable {
-  constructor() {
+class DB {
+  // options;
+  constructor(options) {
     // TODO
+    // super();
+    this.options = options;
+
+    this.hook = new AsyncSeriesWaterfallHook(["res"]);
+    /**
+     * 保存每一步回调操作的正常结果
+     */
+    this.values = [];
   }
 
-  request() {
-    // TODO
+  request(options) {
+    return new Promise((resolve, reject) => {
+      const finalOps = {};
+      Object.assign(finalOps, options, this.options);
+
+      this.hook.callAsync(finalOps, (err, res) => {
+        // judge一般都会是最后一个回调
+        const prevRes = this.values.slice(0, this.values.length - 1).pop();
+
+        // err || err === undefined 验证reject空和非空
+        // res === true 验证中断
+        if (err || err === undefined || res === true) reject(prevRes);
+        else {
+          resolve(res);
+        }
+      });
+    });
+  }
+
+  plugin(name, callback) {
+    this.hook.tapPromise(name, async (...args) => {
+      // 为了保存中间结果，返回new Promise
+      // 为了把同步回调都转成异步使用await
+      const res = await callback(...args);
+
+      // console.log("callback", res);
+      //回调中返回的undefined不保存
+      if (res !== undefined) this.values.push(res);
+
+      return new Promise((resolve, reject) => {
+        resolve(res);
+      });
+    });
   }
 }
 
-module.exports = DB
+module.exports = DB;

package.json

@@ -28,6 +28,7 @@
     "webpack": "^3.5.3"
   },
   "dependencies": {
-    "puppeteer": "^16.2.0"
+    "puppeteer": "^16.2.0",
+    "tapable": "^2.2.1"
   }
 }