<!--
//--------------------------随机字符--------------------------
//str_0 长度
//str_1 是否大写字母
//str_2 是否小写字母
//str_3 是否数字
function rnd_str(str_0,str_1,str_2,str_3)
{
var Seed_array=new Array();
var seedary;
var i;

Seed_array[0]=""
Seed_array[1]= "A B C D E F G H I J K L M N O P Q R S T U V W X Y Z";
Seed_array[2]= "a b c d e f g h i j k l m n o p q r s t u v w x y z";
Seed_array[3]= "0 1 2 3 4 5 6 7 8 9";


if (!str_1&&!str_2&&!str_3){str_1=true;str_2=true;str_3=true;}

if (str_1){Seed_array[0]+=Seed_array[1];}
if (str_2){Seed_array[0]+=" "+Seed_array[2];}
if (str_3){Seed_array[0]+=" "+Seed_array[3];}

Seed_array[0]= Seed_array[0].split(" ");
seedary=""
for (i=0;i<str_0;i++)
{
seedary+=Seed_array[0][Math.round(Math.random( )*(Seed_array[0].length-1))]
}
return(seedary);

}
-->


//--------------------调用时--------------

<script language="JavaScript" type="text/JavaScript">
var obj=document.all.jz_4;
var tmp=rnd_str(6,true,true,true);
obj.value=tmp;
document.write(tmp);
</script>