<form name="form1"  >
  <input name="text1" type="text" id="text1" size="10">
  <input type="submit" name="Submit" onClick="num()" >
</form>
<script language="javascript">
 function num()
 {    var flag1=false;
      var compStr="4567839012";
      var a=from1.text1.value;
      var length2=a.length;
      for (var iIndex=0;iIndex<length2;iIndex++)
   {    var temp1=compStr.indexOf(a.charAt(iIndex));
  if(temp1==-1)
  { flag1=false;
   alert("不对") ;
   break;      
  } else
  {flag1=true;} } return flag1; }
</script>

var temp1 应该定义在FOR循环外面

你写的东东真行了！！根本句没什么用
[CODE]
<form name="form1" >
<input name="text1" type="text" id="text1" size="10">
<input type="submit" name="Submit" onClick="num()" >
</form>
<script language="javascript">
function num()
{
var flag1=false;
var compStr="4567839012";
var a=form1.text1.value;
var length2=a.length;
for (var iIndex=0;iIndex<length2;iIndex++)
{
var temp1=compStr.indexOf(a.charAt(iIndex));
if(temp1==-1)
{
flag1=false;
alert("不对") ;
break;
}
else
{
flag1=true;
}
}
return flag1;
}
</script>
[/CODE]