react-selector-hooks's Introduction

react-selector-hooks

Collection of hook-based memoized selector factories for declarations outside of render.

Motivation

Reusing existing functions. It also might often be desirable to declare selector functions outside of render to keep render functions less bloated.

Instead of this:

function Component({ a, b }) {
  const memoizedValue = useMemo(() => computeExpensiveValue(a, b), [a, b])
  return <span>{memoizedValue}</span>
}

You can write this:

const useSelector = createSelector(computeExpensiveValue)

function Component({ a, b }) {
  const memoizedValue = useSelector(a, b)
  return <span>{memoizedValue}</span>
}

API

createSelector(resultFunc)

import * as React from 'react'
import { createSelector } from 'react-selector-hooks'

const useSelector = createSelector(computeExpensiveValue)

export default function Component({ a, b }) {
  const memoizedValue = useSelector(a, b)
  return <span>{memoizedValue}</span>
}

createStateSelector([inputSelectors], resultFunc)

This is really similar to reselect's createSelector.

import * as React from 'react'
import { createStateSelector } from 'react-selector-hooks'

const useSelector = createStateSelector(
  [
    state => state.values.value1,
    (state, a) => state.values.value2 + a,
    (state, a) => state.values.value3 * a,
  ],
  (value1, value2, value3) => value1 + value2,
)

export default function Component({ a }) {
  const state = React.useContext(StoreContext)
  const memoizedValue = useSelector(state, a)
  return <span>{memoizedValue}</span>
}

createStructuredSelector({...inputSelectors}, resultFunc)

This is really similar to reselect's createStructuredSelector.

import * as React from 'react'
import { createStructuredSelector } from 'react-selector-hooks'

const useSelector = createStructuredSelector(
  {
    value1: state => state.values.value1,
    value2: (state, a) => state.values.value2 + a,
  },
  ({ value1, value2 }) => value1 + value2,
)

export default function Component({ a }) {
  const state = React.useContext(StoreContext)
  const memoizedValue = useSelector(state, a)
  return <span>{memoizedValue}</span>
}

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