关于jquery页面自动跳转的问题

<div id="BellPhone">
<br>
<span id="PortInPstnLabel">住址电话：</span>
<input id="BellPhone1" type="text" style="width: 32px;" size="3" maxlength="3" name="BellPhone1" class="bell" >-
<input id="BellPhone2" type="text" style="width: 32px;" size="3" maxlength="3" name="BellPhone2" class="bell">-
<input id="BellPhone3" type="text" style="width: 40px;" size="4" maxlength="4" name="BellPhone3" class="bell">
</div>

$(".bell").keyup(function () {

var length = $(this).val().length;

if (length == "3") {

$(this).next(".bell").focus();

}

})