diff --git a/docs/generator.md b/docs/generator.md
index 52ed278..349480e 100644
--- a/docs/generator.md
+++ b/docs/generator.md
@@ -71,7 +71,7 @@ hw.next()
 需要注意的是，`yield`语句后面的表达式，只有当调用`next`方法、内部指针指向该语句时才会执行，因此等于为JavaScript提供了手动的“惰性求值”（Lazy Evaluation）的语法功能。
 
 ```javascript
-function* gen{
+function* gen() {
   yield  123 + 456;
 }
 ```
diff --git a/docs/promise.md b/docs/promise.md
index eb45901..9ebc4c9 100644
--- a/docs/promise.md
+++ b/docs/promise.md
@@ -101,6 +101,9 @@ var getJSON = function(url) {
     client.send();
 
     function handler() {
+      if ( this.readyState !== 4 ) {
+        return;
+      }
       if (this.status === 200) {
         resolve(this.response);
       } else {