<!DOCTYPE html> 
<html> 
<head> 
<meta charset="UTF-8"> 
<title>test javascript</title> 
<script type="text/javascript"> 
window.onload = function() { 
var EventUtil = { 
addhandler:function(element,type,handler) { 
if(element.addEventListenter) { 
element.addEventListenter(type,handler,false); 
} else if (element.attachEvent) { 
element.attachEvent("on"+type,handler); 
} else { 
element["on"+type] = handler; 
} 
}, 

getEvent:function(event) { 
return event?event:window.event; 
}, 

getTarget:function() { 
return event.target || event.srcElement; 
}, 

preventDefault:function() { 
if(event.preventDefault) { 
event.preventDefault(); 
} else { 
event.returnValue = false; 
} 
}, 

stopPropagation:function() { 
if(event.stopPropagation) { 
event.stopPropagation(); 
} else { 
event.cancelBuddle = true; 
} 
}, 

removehandler:function(element,type,handler) { 
if(element.removeEventListenter) { 
element.addEventListenter(type,handler,false); 
} else if (element.detachEvent) { 
element.detachEvent("on"+type,handler); 
} else { 
element["on"+type] = null; 
} 
}, 

getCharCode: function(event) { 
if(typeof event.charCode == "number") { 
return event.charCode; 
} else { 
return event.keyCode; 
} 
}, 

getClipboardText: function(event) { 
var clipboardData = event.clipboardData || window.clipboardData; 
return clipboardData.getData("text"); 
}, 

setClipboardText: function(event,value) { 
if(event.clipboardData) { 
return event.clipboardData.setData("text/plain",value); 
} else if(window.clipboardData){ 
return window.clipboardData.setData("text",value); 
} 
} 

} 

var textarea = document.forms[0].elements["text"]; 
var button = document.getElementById("button"); 


(function() { 
function tabForward(event) { 
event = EventUtil.getEvent(event); 
var target = EventUtil.getTarget(event); 

if(target.value.length == target.maxLength) { 
var form = target.parentElement; 

for(var i=0,len = form.elements.length;i<len-1;i++) { 
if(form.elements[i] == target) { 
form.elements[i+1].focus(); 
return ; 
} 
} 
} 

} 

var textTel1 = document.getElementById("txtTel1"); 
var textTel2 = document.getElementById("txtTel2"); 
var textTel3 = document.getElementById("txtTel3"); 

EventUtil.addhandler(textTel1,"keyup",tabForward); 
EventUtil.addhandler(textTel2,"keyup",tabForward); 
EventUtil.addhandler(textTel3,"keyup",tabForward); 

})(); 
} 
</script> 
</head> 
<body> 
<form> 
<input type="text" name="tel1" id="txtTel1" maxlength="3" /> 
<input type="text" name="tel2" id="txtTel2" maxlength="3" /> 
<input type="text" name="tel3" id="txtTel3" maxlength="3" /> 
</form> 
</body> 
</html>