title向左_右滚动效果

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>我爱自己想</title>
<script type="text/javascript">
    //效果:向左,向右滚动.
   //setInterval事件.
   var dir='left';

   setInterval(function (){

       if(dir==='left'){
      //实现向左滚动
        var firstDoc=document.title.charAt(0);
        var others=document.title.substring(1,document.title.length);
       document.title=others+firstDoc;

       }else if(dir==='right'){

       var lastDoc=document.title.charAt(document.title.length-1);

       var others=document.title.substring(0,document.title.length-1);

       document.title=lastDoc+others;   }
      },1000);

   //为两个button注册单击事件
     window.onload=function (){
      //left:
      document.getElementById('idLeft').onclick=function (){
        dir='left';
       }
     //right;
       document.getElementById('idright').onclick=function (){
        dir='right';
      }
   }
</script>
</head>

<body>
    <input type="button" name="name" value="left" id="idLeft" onclick="leftMoths()"></input>
    <input type="button" name="name" value="right" id="idright" onclick="rightMoths()"></input>

</body>
</html>