请教各位哪里不对?
Dleno 2004-06-23 05:11:22 以下是代码:
<script language="javascript">
function checknum(){
str=document.f1.num.value;
for(i=0; i<str.length; i++){
chr=str.substring(i, i++);
if(chr<"0"||chr>"9"){
alert("请输入数字字符!");
break;
}
}
}
</script>
<form action="" method="post" name="f1">
<input name="num">
<input type="submit" value="提交" onclick="checknum()">
</form>