关于在文本输入框定义输入格式的问题

1<style type="text/css">   
2input {background-color: #ffffff; border-bottom: #000000 1px solid; border-left: #ffffff 0px solid; border-right: #ffffff 0px solid; border-top: #ffffff 0px solid; color: #000000; font-size: 9pt }   
3</style>

1<form>
2<input maxlength="3" name="ip1" size="3" type="text"/>.   
3<input maxlength="3" name="ip2" size="3" type="text"/>.   
4<input maxlength="3" name="ip3" size="3" type="text"/>.   
5<input maxlength="3" name="ip4" size="3" type="text"/>
6</form>

1<input maxlength="10" name="ddd" onfacos="ff()" onkeyup="cc(this)" onpaste="return false;" size="10" type="text"/>

 1<script language="Javascript">   
 2function ff() //控制光标位置   
 3{   
 4var e = event.srcElement;   
 5var r =e.createTextRange();   
 6r.moveStart('character',e.value.length);   
 7r.collapse(true);   
 8r.select();   
 9}   
10function cc(tt)   
11{   
12if(!(event.keyCode==8 ¦ ¦ event.keyCode==46)){ //允许删除   
13switch (tt.value.length){   
14case 4 :   
15tt.value = tt.value+"-"   
16break;   
17case 7 :   
18tt.value = tt.value+"-"   
19break;   
20}   
21}   
22tt.focus();   
23}   
24</script>