javascript数组如何删除相同元素

<script type="text/javascript">

var student = ['qiang','ming','tao','li','liang','you','qiang','tao'];

function unique(arr){

var tmp = new Array();

for(var m in arr){

tmp[arr[m]]=1;

}

//再把键和值的位置再次调换

var tmparr = new Array();

for(var n in tmp){

tmparr.push(n);

}

return tmparr;

}

</script>