数组去重

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

for(var  a = 0 ; a < arr.length; a++){

  for(var b = a+1;b< arr.length ; b++){

     if(arr[a]==arr[b]){

      arr.s

}

}

}