var arr = [1,2,2,3,5,4,8,6,4,2,47,5,9,3,20,3];

//将数组转为对象，将key入对象，对象中key值不允许重复

var toNewObject = function(arr){

var obj = {};

var len= arr.length;

for(var i = 0;i<len;i++){

obj[arr[i]] = true;

}

return obj;

}

//对象转成数组

var toNewArr = function(obj){

var arr =[];

for(var attr in obj){

if(obj.hasOwnProperty(attr)){

arr.push(attr);

}

}

return arr;

}

//通过函数输出筛迭后的数组

var unique = function(arr){

var obj = toNewObject(arr);

var newArr = toNewArr(obj);

return newArr;

}

console.log(unique(arr));