不知道做的对不对..puye

lib/index.js

@@ -3,16 +3,50 @@
   class Delegator {
     constructor (selector/* root选择器 */) {
       // TODO
+      this.stack = {};
+      this.root  = document.querySelector(selector);
+      this.delegate = null;
     }
 
     on (event/* 绑定事件 */, selector/* 触发事件节点对应选择器 */, fn/* 出发函数 */) {
       // TODO
+      if(this.stack[selector] === undefined)
+        this.stack[selector] = [];
+
+      this.stack.push(fn)
+
+      // 链式调用时，移除先前的on传入的出发函数
+      if ( this.delegate != null ){
+        this.root.removeEventListener(event, this.delegate)
+      }
+      // 查出满足selector的dom
+      this.delegate = (e) => {
+        var i = 0;
+        while (i < e.path.length) {
+          for(let sel in this.stack){
+            if(e.path[i].matches(sel)){
+              this.stack[sel].forEach(fn => {
+                fn.call(e.path[i], e)
+              });
+            }
+          }
+          i++;
+        }
+      }
+      this.root.addEventListener(event, this.delegate)
+      return this;
     }
 
     destroy () {
       // TODO
+      this.root.removeEventListener(event, this.delegate);
+      this.delegate = null;
+      this.stack = {}
     }
-  }
+  } 
 
   root.Delegator = Delegator
-}(window, document)
+}(window, document)
+
+
+