function random(min,max){
return Math.floor(min+Math.random()*(max-min));
}
var awardListDom=document.getElementById("awardListDom"),num=document.getElementById("num"),submit=document.getElementById("submit");
var awardList=["一等奖","二等奖","三等奖","鼓励奖","谢谢参与","谢谢参与"];

awardListDom.value=awardList;
submit.onclick=function(){
//引用数组
var oldArray=awardList;
var rNum=random(0,oldArray.length);

if(oldArray.length<1){
awardListDom.value="活动结束";
num.value="活动结束";
}
else{
num.value=oldArray[rNum];
oldArray.splice(rNum,1);
awardListDom.value=oldArray;
}
}