请问一个加密的问题,生成八位不重复字符

var code;

function getcode(){

	

       code = "";   

       var codeLength = 8;

       var selectChar = new Array(1,2,3,4,5,6,7,8,9,'A','B','C','D','E','F','G','H','I','J','K','L','M','N','P','Q','R','S','T','U','V','W','X','Y','Z');  

       for(var i=0;i<codeLength;i++)   

       {   

           

       var charIndex = Math.floor(Math.random()*34);   

       code +=selectChar[charIndex];   

          

       }   

	

	return code;

	

	

}

var endcode;

endcode=Math.random()+getcode();

document.write(endcode)



//显示结果   0.42290559902354274Z8FLZEU5 

 function getcode()

		dim num1,rndnum,t,nn

		  Randomize

			Do While Len(rndnum)<6

			num1=CStr(Chr((57-48)*rnd+48))

			rndnum=rndnum&num1

			loop

			t=time()

			nn=second(t)&rndnum

			'T变量是当前的时间转换,所以不可能有重复的.

			n=n&nn

		getcode=n

		end function

		

		response.write getcode()