js在数组中删除重复的元素自保留一个（两种实现思路）

例如：var student = [‘qiang","ming","tao","li","liang","you","qiang","tao"];
第一种思路是：遍历要删除的数组arr, 把元素分别放入另一个数组tmp中，在判断该元素在arr中不存在才允许放入tmp中
用到两个函数：for ...in 和 indexOf（）

<script type="text/javascript"> var student = ["qiang","ming","tao","li","liang","you","qiang","tao"];function unique（arr）{// 遍历arr，把元素分别放入tmp数组（不存在才放）var tmp = new Array（）;for（var i in arr）{//该元素在tmp内部不存在才允许追加if（tmp.indexOf（arr[i]）==-1）{tmp.push（arr[i]）;}}return tmp;}</script>

第二种思路是：把目标数组arr的元素值和键的位置调换自动就把重复的元素给删除掉了，调换后的样子：array（"qiang"=>1,"ming"=>1,"tao"=>1）

<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>