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awaisab172 · Nov 7, 2012 · 00d63c9 · 00d63c9
1 parent 1f5854c
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Showing 3 changed files with 67 additions and 3 deletions.
diff --git a/Chapter07-The-Factory-Pattern/7.03 - XHR factory example.js b/Chapter07-The-Factory-Pattern/7.03 - XHR factory example.js
@@ -33,8 +33,8 @@ SimpleHandler.prototype = {
         continue;
       }
       // If we reach this point, method[i] worked.
-      this.createXhrObject = methods[i]; // Memoize the method.
-      return methods[i];
+      this.createXhrObject = methods[i]; // Memoize the method.  记住该方法
+      return methods[i]();  // 原书中的代码少了一对括号，这里需要多加一对括号才可以正确返回XMLHttpRequeset
     }
 
     // If we reach this point, none of the methods worked.

diff --git a/Chapter08-The-Bridge-Pattern/8.01 - Event listener example.js b/Chapter08-The-Bridge-Pattern/8.01 - Event listener example.js
@@ -7,14 +7,16 @@ function getBeerById(e) {
   });
 }
 
+// 把事件处理的语句封装到回调函数中，现在我们通过接口而不是实现进行编程
+// getBeerById并没有和事件对象捆绑在一起。
 function getBeerById(id, callback) {
   // Make request for beer by ID, then return the beer data.
   asyncRequest('GET', 'beer.uri?id=' + id, function(resp) {
     // callback response
     callback(resp.responseText);
   });
 }
-
+// 桥接器的使用：事件监听器回调函数
 addEvent(element, 'click', getBeerByIdBridge);
 function getBeerByIdBridge (e) {
   getBeerById(this.id, function(beer) {

diff --git a/index.html b/index.html
@@ -0,0 +1,62 @@
+<html>
+<head>
+
+</head>
+<body>
+<script>
+/* AjaxHandler interface. */
+
+// var AjaxHandler = new Interface('AjaxHandler', ['request', 'createXhrObject']);
+
+/* SimpleHandler class. */
+
+var SimpleHandler = function() {}; // implements AjaxHandler
+SimpleHandler.prototype = {
+  request: function(method, url, callback, postVars) {
+    var xhr = this.createXhrObject();
+    xhr.onreadystatechange = function() {
+      if(xhr.readyState !== 4) return;
+      (xhr.status === 200) ? 
+        callback.success(xhr.responseText, xhr.responseXML) : 
+        callback.failure(xhr.status);
+    };
+    xhr.open(method, url, true);
+    if(method !== 'POST') postVars = null;
+    xhr.send(postVars);
+  },
+  createXhrObject: function() { // Factory method.
+    var methods = [
+      function() { return new XMLHttpRequest(); },
+      function() { return new ActiveXObject('Msxml2.XMLHTTP'); },
+      function() { return new ActiveXObject('Microsoft.XMLHTTP'); }
+    ];
+
+    for(var i = 0, len = methods.length; i < len; i++) {
+      try {
+        methods[i]();
+      }
+      catch(e) {
+        continue;
+      }
+      // If we reach this point, method[i] worked.
+      this.createXhrObject = methods[i]; // Memoize the method.  记住该方法
+      return methods[i]();
+    }
+
+    // If we reach this point, none of the methods worked.
+    throw new Error('SimpleHandler: Could not create an XHR object.');
+  } 
+};
+
+/* Usage. */
+
+var myHandler = new SimpleHandler();
+var callback = { 
+  success: function(responseText) { alert('Success: ' + responseText); }, 
+  failure: function(statusCode) { alert('Failure: ' + statusCode); } 
+};
+myHandler.request('GET', 'script.php', callback);
+
+</script>
+</body>
+</html>