var arr = [1, 3, 5, 2, 2, 5, 6, 7, 8, 3, 4, 5, 6, 8, 9, 6]


function uniqueArray(array) {
  array.sort()
  return array.reduce((prev, item, index) => {
    if (prev[prev.length - 1] !== item) {
      prev.push(item);
    }
    return prev;
  }, [])
}

function uniqueArray(array) {
  var _arr = [],
    map = new Map();

  for (var i = 0; i < array.length; i++) {
    if (!map.get(array[i])) {
      map.set(array[i], 1)
      _arr.push(array[i])
    }
  }
  return _arr
}

function uniqueArray(array) {
  var _arr = [],
    obj = {};

  for (var i = 0; i < array.length; i++) {
    if (!obj[array[i]]) {
      obj[array[i]] = 1;
      _arr.push(array[i])
    }
  }
  return _arr
}


function uniqueArray(array) {
  return Array.from(new Set(array))
}

console.log(uniqueArray(arr))