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                        /前端开发
                        
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                        /JavaScript进阶篇

document.getELementById is not a function?怎么回事？

<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>计时器</title>

</head>
<body>
<form>
    <input type="text" id="clock" size="50" />
    <input type="button" value="Start" id="start"/>
    <input type="button" value="Stop" id="stop"/>
</form>
<script type="text/javascript">

   var attime;
   var ostart=document.getELementById('start');
   var ostop=document.getELementById('stop');
   var timer=null;
   ostart.onclick=function start(){
       clearInterval(timer);
       timer=setInterval(function(){
           var time=new Date();
           attime=time.getHours()+":"+   time.getMinutes()+":"+ time.getSeconds();
           document.getElementById("clock").value = attime;
       },1000);
   }


</script>
</body>
</html>