文本框的问题

Question

<script>
var  timer=null;
function check(uid)
{
var obj=document.all(uid);
if(isNaN(obj.value)&&(obj.value!="-"))
obj.value=obj.value.slice(0,-1);
else
if(obj.value.indexOf(".")>-1)
if(obj.value.indexOf(".")<obj.value.length-3)
obj.value=obj.value.slice(0,-1);
timer=setTimeout("check('"+uid+"')",10);
}
function clear(){
clearTimeout(timer);
}
</script>
<form name=form1>
<input name=mytext onfocus=check(this.uniqueID) onblur=clear()>
<input name=mytext onfocus=check(this.uniqueID) onblur=clear()>
<input name=mytext onfocus=check(this.uniqueID) onblur=clear()>
输入过程中即时检查文本框
</form>

Answer 1

<script>
function aa(obj){
var par =/[^0-9.]/
if(par.test(obj)){alert("wrong");return}
if(ifNan(obj.charAt(obj.length-1)||ifNan(obj.charAt(obj.length-2)||obj.charAt(obj.length-3)!="."){
alert("wrong");return}
}
</script><form name=form1>
<input type=text name=text1 onchange=aa(document.form1.text1.value>
</form>