Merge pull request reactjs#2 from michaelrp/patch-1

Adding validation check to `handleSubmit`.

Author: chenglou

scripts/example.js

@@ -89,13 +89,17 @@ var CommentList = React.createClass({
 });
 
 var CommentForm = React.createClass({
-  handleSubmit: function() {
+  handleSubmit: function(e) {
+    e.preventDefault();
     var author = this.refs.author.getDOMNode().value.trim();
     var text = this.refs.text.getDOMNode().value.trim();
+    if (!text || !author) {
+      return;
+    }
     this.props.onCommentSubmit({author: author, text: text});
     this.refs.author.getDOMNode().value = '';
     this.refs.text.getDOMNode().value = '';
-    return false;
+    return;
   },
   render: function() {
     return (