code: function diff(arr, remove) {
    if (arr == null) {
      return [];
    }
  
    if (remove == null) {
      return arr;
    }
  
    var res = [];
    var len = arr.length;
    var i = 0;
  
    while (i < len) {
      var ele = arr[i++];
  
      if (remove.indexOf(ele) === -1) {
        res.push(ele);
      }
    }
  
    return res;
  }
docs: Remove unwanted elements and uniquify the
  given `array`.
  
  @param  {Array} `array` The array to uniquify
  @return {Array} `remove` Array of elements to remove
  @api private