Redux / Reselect选择器重用

Question

我对选择器很陌生。我创造了以下几个方面：

import { createSelector } from 'reselect';

const getValues = (state) => state.grid; // [3, 4, 7, 3, 2, 7, 3,...]
const getTiles = (state) => state.tiles; // [0, 1, 0, 1, 0, 0, 1,...]

// counts selected tiles (ie. adds up all the 1s)
export const getSelected = createSelector(
  [getTiles],
  tiles => tiles.reduce((acc, elem) => acc + elem, 0)
);

// displays only values of selected tiles, for the rest it shows 0
export const showSelected = createSelector(
  [getTiles, getValues],
  (tiles, grid) => tiles.map((idx, i) => (idx === 1 ? grid[i] : 0))
);



  export const addSelected = createSelector(
  [showSelected]
  .....
);

/*
export const addSelected = createSelector(
  [showSelected],
  coun => coun.reduce((acc, elem) => acc + elem, 0)
);

*/

第三个选择器(addSelected --最后一个底部的注释输出版本)基本上与第一个选择器(输入不同)的操作相同。我如何使它变得更通用，这样我就可以重用它，而不用再写整行的“减少”行了？

Answer 1

您只需将减缩部分提取到它自己的函数中，如下所示：

import { createSelector } from 'reselect'

...

// addElements adds all elements from given array
const addElements = elements =>
  elements.reduce((acc, elem) => acc + elem, 0)

export const getSelected = createSelector([getTiles], addElements)

export const addSelected = createSelector([showSelected], addElements)

希望这能帮上忙。