Reselect 介绍
Reselect 是一个 Redux 的选择器库，灵感来源于 NuclearJS
。
-
Selector 可以计算衍生的数据，可以让 Redux 存储尽可能少的 state 。
-
Selector 非常高效，除非某个参数发生变化，否则不会发生计算过程。
-
Selector 是可组合的，它们可以输入、传递到其他的选择器。
示例：
import { createSelector } from 'reselect'
const shopItemsSelector = state => state.shop.items
const taxPercentSelector = state => state.shop.taxPercent
const subtotalSelector = createSelector(
shopItemsSelector,
items => items.reduce((acc, item) => acc + item.value, 0)
)
const taxSelector = createSelector(
subtotalSelector,
taxPercentSelector,
(subtotal, taxPercent) => subtotal * (taxPercent / 100)
)
export const totalSelector = createSelector(
subtotalSelector,
taxSelector,
(subtotal, tax) => ({ total: subtotal + tax })
)
let exampleState = {
shop: {
taxPercent: 8,
items: [
{ name: 'apple', value: 1.20 },
{ name: 'orange', value: 0.95 },
]
}
}
console.log(subtotalSelector(exampleState)) // 2.15
console.log(taxSelector(exampleState)) // 0.172
console.log(totalSelector(exampleState)) // { total: 2.322 }