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