react-code-dataset / reselect /docs /examples /handling-empty-array-results /fallbackToEmptyArray.ts
| import { createSelector } from 'reselect' | |
| import type { RootState } from './firstPattern' | |
| const EMPTY_ARRAY: [] = [] | |
| export const fallbackToEmptyArray = <T>(array: T[]) => { | |
| return array.length === 0 ? EMPTY_ARRAY : array | |
| } | |
| const selectCompletedTodos = createSelector( | |
| [(state: RootState) => state.todos], | |
| todos => { | |
| return fallbackToEmptyArray(todos.filter(todo => todo.completed === true)) | |
| } | |
| ) | |