added iterator pattern

chuanxshi · chuanxshi · commit db9d611370e7 · 2011-12-16T10:23:20.000+08:00
diff --git a/design-patterns/iterator.html b/design-patterns/iterator.html
@@ -0,0 +1,63 @@
+<!doctype html>
+<html lang="en">
+<head>
+<title>JavaScript Patterns</title>
+<meta charset="utf-8">
+</head>
+<body>
+<script>
+var element;
+while (element - agg.next()) {
+  // do something with the element
+  console.log(element);
+}
+
+while (agg.hasNext()) {
+  // do something with the next element...
+  console.log(agg.next());
+}
+
+var agg = (function () {
+  
+  var index = 0,
+      data = [1, 2, 3, 4, 5],
+      length = data.length;
+      
+  return {
+    
+    next: function () {
+        var element;
+        if (!this.hasNext()) {
+          return null;
+        }
+        element = data[index];
+        index = index + 2;
+        return element;
+    },
+    
+    hasNext: function () {
+      return index < length;
+    },
+    
+    rewind: function () {
+      index = 0;
+    },
+    
+    current: function () {
+      return data[index];
+    }
+  
+  };
+}());
+
+// this loop logs 1, then 3, then 5
+while (agg.hasNext()) {
+  console.log(agg.next());
+}
+
+// go back
+agg.rewind();
+console.log(agg.current()); // 1
+</script>
+</body>
+</html>
