Redux / Reselect - 选择器重用

Question

我是选择器的新手。我创建了以下：

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，注释掉的版本）基本上与第一个选择器做同样的事情（不同的输入）。我怎样才能使它更通用，以便我可以重用它而不是再次编写整个 'reduce' 行？

Answer 1

您可以像这样将 reduce 部分提取到它自己的函数中：

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)

希望对您有所帮助。

Redux / Reselect - 选择器重用

Redux / Reselect - selector reusing

redux

reselect