html5 生成随机数 html生成随机数代码

生成随机数：
var chars = ['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', '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', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9'];
function GenerateRandomNum(n) {
       var res = "";
       for (var i = 0; i < n; i++) {
            var id = Math.ceil(Math.random() * 61);
            res += chars[id];
       }
       return res;
} 
生成验证码：
<style type=text/css>
    .spn_yzm{border: #ff0000 1px solid; font-size: 14px; padding-left:8px;padding-right:8px;margin-left:8px}
</style<span id="ValidateCode1" class="spn_yzm"></span> //html中的验证码标签
    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]= "0 1 2 3 4";
        Seed_array[2]= "5 6 7 8 9"; 
        Seed_array[3]= "a b c d";         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); 
    }     function CreateValidateCode()
    {
        var elemspan1 = document.getElementById("ValidateCode1");
        elemspan1.innerHTML = rnd_str(4,true,true,true);
    }