gragland

import React, { useState, useEffect, useContext, createContext } from "react";
import Auth0 from "auth0-js";

/*
    SETUP INSTRUCTIONS:
    - Create a new Auth0 application and choose type "Single Page Web Applications"
    - Go to your news app's setting and add the domain and clientId to the code below
      where it says "Replace me".
    - In your new apps settings scroll to the bottom, click "Show Advanced Settings",
      go to the "Grant Types" tab, check the "Password" option, then click save.

gragland

// Top level App component
import React from "react";
import { ProvideAuth } from "./use-auth.js";

function App(props) {
  return (
    <ProvideAuth>
      {/* 
        Route components here, depending on how your app is structured.
        If using Next.js this would be /pages/_app.js

gragland

import Router from 'next/router';
import Analytics from 'analytics';
import googleAnalyticsPlugin from 'analytics-plugin-ga';

const analytics = Analytics({
  debug: process.env.NODE_ENV !== 'production',
  plugins: [
    googleAnalyticsPlugin({
      trackingId: process.env.GA_TRACKING_ID
    })

gragland

import { useState, useCallback, useRef } from "react";

// Usage
function App() {
  const [hoverRef, isHovered] = useHover();

  return (
    <div ref={hoverRef}>
      {isHovered ? '😁' : '☹️'}
    </div>

gragland

import { useState, useRef, useEffect, useCallback } from 'react';

// Usage
function App(){
  // State for storing mouse coordinates
  const [coords, setCoords] = useState({ x: 0, y: 0 });
  
  // Event handler utilizing useCallback ...
  // ... so that reference never changes.
  const handler = useCallback(

gragland

// Current auth status
let currentAuth = false;

// Holds setAuth for every instance of hook
const authSetters = new Set();

function useFakeAuth() {
  // Auth state and setter
  const [auth, setAuth] = useState(currentAuth);

gragland

import { useState, useEffect, useRef } from 'react';

// Let's pretend this <Counter> component is expensive to re-render so ...
// ... we wrap with React.memo, but we're still seeing performance issues :/
// So we add useWhyDidYouUpdate and check our console to see what's going on.
const Counter = React.memo(props => {
  useWhyDidYouUpdate('Counter', props);
  return <div style={props.style}>{props.count}</div>;
});

gragland

import { useState, useEffect, useRef } from 'react';

// Let's pretend this <Counter> component is expensive to re-render so ...
// ... we wrap with React.memo, but we're still seeing performance issues :/
// So we add useWhyDidYouUpdate and check our console to see what's going on.
const Counter = React.memo(props => {
  useWhyDidYouUpdate('Counter', props);
  return <div style={props.style}>{props.count}</div>;
});

gragland

// Usage
function App() {
  const [darkMode, setDarkMode] = useDarkMode();

  return (
    <div>
      <div className="navbar">
        <Toggle darkMode={darkMode} setDarkMode={setDarkMode} />
      </div>
      <Content />

gragland

import { useState, useEffect } from 'react';

function App() {
  const columnCount = useMedia(
    // Media queries
    ['(min-width: 1500px)', '(min-width: 1000px)', '(min-width: 600px)'],
    // Column counts (relates to above media queries by array index)
    [5, 4, 3],
    // Default column count
    2