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⚠️ This article was written in 2020. Some content may be outdated.

React Hooks: Custom Hook Patterns

When it comes to custom Hook patterns in React Hooks, many developers only operate at the API-call level. This article tries to look at the problems you'll actually run into and their solutions from a production perspective.

Basic Principles ​

Building on this, we can optimize further:

javascript
import { useReducer, useCallback } from 'react'

const initialState = { items: [], filter: '', sort: 'date' }

function reducer(state, action) {
  switch (action.type) {
    case 'SET_ITEMS': return { ...state, items: action.payload }
    case 'SET_FILTER': return { ...state, filter: action.payload }
    case 'ADD_ITEM': return { ...state, items: [...state.items, action.payload] }
    case 'REMOVE_ITEM': return { ...state, items: state.items.filter(i => i.id !== action.payload) }
    default: throw new Error(`Unknown: ${action.type}`)
  }
}

This pattern is very useful in large projects and noticeably lowers maintenance cost.

Advanced Features ​

In real projects, usage gets a bit more complex:

javascript
import { useReducer, useCallback } from 'react'

const initialState = { items: [], filter: '', sort: 'date' }

function reducer(state, action) {
  switch (action.type) {
    case 'SET_ITEMS': return { ...state, items: action.payload }
    case 'SET_FILTER': return { ...state, filter: action.payload }
    case 'ADD_ITEM': return { ...state, items: [...state.items, action.payload] }
    case 'REMOVE_ITEM': return { ...state, items: state.items.filter(i => i.id !== action.payload) }
    default: throw new Error(`Unknown: ${action.type}`)
  }
}

This way, both the testability and extensibility of the code improve.

Project Practice ​

Here is a complete example:

javascript
import { useReducer, useCallback } from 'react'

const initialState = { items: [], filter: '', sort: 'date' }

function reducer(state, action) {
  switch (action.type) {
    case 'SET_ITEMS': return { ...state, items: action.payload }
    case 'SET_FILTER': return { ...state, filter: action.payload }
    case 'ADD_ITEM': return { ...state, items: [...state.items, action.payload] }
    case 'REMOVE_ITEM': return { ...state, items: state.items.filter(i => i.id !== action.payload) }
    default: throw new Error(`Unknown: ${action.type}`)
  }
}

Pay attention to edge-case handling — it's critical in production.

Best Practices ​

The key is understanding the core logic:

javascript
import { useReducer, useCallback } from 'react'

const initialState = { items: [], filter: '', sort: 'date' }

function reducer(state, action) {
  switch (action.type) {
    case 'SET_ITEMS': return { ...state, items: action.payload }
    case 'SET_FILTER': return { ...state, filter: action.payload }
    case 'ADD_ITEM': return { ...state, items: [...state.items, action.payload] }
    case 'REMOVE_ITEM': return { ...state, items: state.items.filter(i => i.id !== action.payload) }
    default: throw new Error(`Unknown: ${action.type}`)
  }
}

Performance optimization has to be tied to the specific scenario — not every case calls for over-optimizing.

Common Pitfalls ​

Here's one way we can improve on this:

javascript
import { useReducer, useCallback } from 'react'

const initialState = { items: [], filter: '', sort: 'date' }

function reducer(state, action) {
  switch (action.type) {
    case 'SET_ITEMS': return { ...state, items: action.payload }
    case 'SET_FILTER': return { ...state, filter: action.payload }
    case 'ADD_ITEM': return { ...state, items: [...state.items, action.payload] }
    case 'REMOVE_ITEM': return { ...state, items: state.items.filter(i => i.id !== action.payload) }
    default: throw new Error(`Unknown: ${action.type}`)
  }
}

This approach has been running stably in production for over half a year and has proven itself in practice.

Summary ​

  • Don't adopt new tech just for the sake of using it
  • The code examples are for reference only and should be adapted to your actual use case
  • Custom Hook patterns aren't a silver bullet — choose based on your project's scale and tech stack
  • Understanding the underlying principles matters more than memorizing APIs

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