JavaScript 产生不重复的随机数三种实现思路

<script type="text/javascript">
var count=3000;
var originalArray=new Array;//原数组
//给原数组originalArray赋值
for (var i=0;i<count;i++){
originalArray[i]=i+1;
}
var d1=new Date().getTime();
for (i=0;i<count;i++){
var index=Math.floor(Math.random()*originalArray.length); //随机取一个位置
document.write(index+" , ");
originalArray.splice(index,1);
}
var d2=new Date().getTime();
document.write("运算耗时"+(d2-d1));
</script>

<script type="text/javascript">
var count=3000;
var originalArray=new Array;//原数组
//给原数组originalArray赋值
for (var i=0;i<count;i++){
originalArray[i]=i+1;
}
var d1=new Date().getTime();
for (var num,i=0;i<count;i++){
do{
num=Math.floor(Math.random()*count);
}while(originalArray[num]==null);
document.write(originalArray[num]+" , ");
originalArray[num]=null;
}
var d2=new Date().getTime();
document.write("运算耗时"+(d2-d1));
</script>

<script type="text/javascript">
var count=3000;
var originalArray=new Array;//原数组
//给原数组originalArray赋值
for (var i=0;i<count;i++){
originalArray[i]=i+1;
}
var d1=new Date().getTime();
originalArray.sort(function(){ return 0.5 - Math.random(); });
for (var i=0;i<count;i++){
document.write(originalArray[i]+" , ");
}
var d2=new Date().getTime();
document.write("运算耗时"+(d2-d1));
</script>