js 高效去除数组重复元素

function unique(data){

data = data || [];

var a = {};

for (var i=0; i<data.length; i++) {

var v = data[i];

if (typeof(a[v]) == 'undefined'){

a[v] = 1;

}

};

data.length=0;

for (var i in a){

data[data.length] = i;

}

return data;

}

function test(){

var arr = [9,1,3,8,7,7,6,6,5,7,8,8,7,4,3,1];

var arr1 = unique(arr);

alert(arr1.join(","));

}

test();