added generators function

Author: sgaurav

generators.js

@@ -0,0 +1,14 @@
+function* count(){
+  var start = 0;
+  while(true) {
+    yield start;
+    ++start;
+  }
+}
+
+var iterator = count();
+
+iterator.next(); //{value: 0, done: false}
+iterator.next(); //{value: 1, done: false}
+iterator.next(); //{value: 2, done: false}
+iterator.next(); //{value: 3, done: false}