diff --git a/css/app.css b/css/app.css
index 7dbe10e..3d56034 100644
--- a/css/app.css
+++ b/css/app.css
@@ -354,6 +354,14 @@ body {
 	}
 }
 
+.progress-indicator-2 {
+    position: fixed;
+    top: 0;
+    left: 0;
+    height: 3px;
+    background-color: #0A74DA;
+}
+
 /**
  * okaidia theme for JavaScript, CSS and HTML
  * Loosely based on Monokai textmate theme by http://www.monokai.nl/
diff --git a/docs/function.md b/docs/function.md
index 5c15225..9c001f8 100644
--- a/docs/function.md
+++ b/docs/function.md
@@ -18,7 +18,7 @@ var p = new Point();
 
 任何带有默认值的参数，被视为可选参数。不带默认值的参数，则被视为必需参数。
 
-利用参数默认值，可以指定一个参数不得省略，如果省略就抛出一个错误。
+利用参数默认值，可以指定某一个参数不得省略，如果省略就抛出一个错误。
 
 ```javascript
 
diff --git a/index.html b/index.html
index 8783259..b752ca1 100644
--- a/index.html
+++ b/index.html
@@ -26,6 +26,7 @@
   <div id="loading">Loading ...</div>
   <div id="error">Opps! ... File not found!</div>
   <div id="flip"><div id="pageup">上一章</div><div id="pagedown">下一章</div></div>
+  <div class="progress-indicator-2"></div>
 
   <script>
       // essential settings
diff --git a/js/ditto.js b/js/ditto.js
index 780a3fb..6f90b6b 100644
--- a/js/ditto.js
+++ b/js/ditto.js
@@ -258,6 +258,24 @@ function router() {
 			$('#pagedown').css('display','inline-block');
 		}
 
+		(function(){
+			var $w = $(window);
+			var $prog2 = $('.progress-indicator-2');
+			var wh = $w.height();
+			var h = $('body').height();
+			var sHeight = h - wh;
+			$w.off('scroll');
+			$w.on('scroll', function(){
+				var perc = Math.max(0, Math.min(1, $w.scrollTop()/sHeight));
+				updateProgress(perc);
+			});
+
+			function updateProgress(perc){
+				$prog2.css({width : perc*100 + '%'});
+			}
+
+		}());
+
     }).fail(function() {
         show_error();