JS小疑点，能行马上结贴 _Web Service

JS小问题，能行马上结贴

HTML code


<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>练习123456</title>
    <script type="text/javascript">      
        function turnLeft() {   
            var title = document.title;
            var firstch = title.charAt(0);
            var secondch = title.substring(1, title.length);
            var finalch = secondch + firstch;
            document.title = finalch;
        }
        function turnRight() { 
           var title = document.title;
            var firstch = title.charAt(title.length-1);
            var secondch = title.substring(0, title.length-1);
            var finalch =  firstch +secondch ;
            document.title = finalch;
        }
        function scrollLeft() {
            //clearInterval(scrollRight);
            var scrollLeft1=setInterval("turnLeft()", 500);
        }
        function scrollRight() {
          // clearInterval(scrollLeft);
            var scrollRight1=setInterval("turnRight()", 500);
        }
        
    </script>
</head>
<body >
 <input  type="button" value="标题向左滚动" onclick="scrollLeft()"  />
  <input type="button" value="标题向右滚动"  onclick="scrollRight()"/>
</body>
</html>

为什么点击向右滚动就行，点击向左滚动却不行

------解决方案--------------------
var secondch = title.substring(1, title.length-1);
------解决方案--------------------

HTML code

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>练习123456</title>
    <script type="text/javascript">      
        function turnLeft() {   
            var title = document.title;
            var firstch = title.charAt(0);
            var secondch = title.substring(1);
            var finalch = secondch+firstch;
            document.title = finalch;

        }
        function turnRight() { 
           var title = document.title;
            var firstch = title.charAt(title.length-1);
            var secondch = title.substring(0, title.length-1);
            var finalch =  firstch +secondch ;
            document.title = finalch;
        }
        function scrollLeft2(){
            var scrollLeft1=setInterval("turnLeft()", 1000);
        }
        function scrollRight() {
            var scrollRight1=setInterval("turnRight()", 1000);
        }  

    </script>
</head>
<body>
  <input type="button" value="标题向左滚动"  onclick="scrollLeft2()" />
  <input type="button" value="标题向右滚动"  onclick="scrollRight()"/>
</body>
</html>

------解决方案--------------------
呵呵 我也不断调试发现的这个问题