Go Fish: Functional State with React Hooks 🎣

Image of a fish hook. So original right?
Image of a fish hook. So original right?

Why use Hooks?

Implementing State with Hooks

Common Types of Hooks

1. The State Hook

import React, { useState } from 'react';function CounterExample() {
const [count, setCount] = useState(0);
return (
<div>
<p>You clicked {count} times</p>
<button onClick={() => setCount(count + 1)}>
Click me
</button>
</div>
);
}

2. The Use Effect Hook

import React, { useState, useEffect } from 'react';function CounterExample() {
const [count, setCount] = useState(0);
useEffect(() => {
document.title = `You clicked ${count} times`;
});
return (
<div>
<p>You clicked {count} times</p>
<button onClick={() => setCount(count + 1)}>
Click me
</button>
</div>
);
}

3. The Custom Hook

import { useState, useEffect } from 'react';

function useFriendStatus(friendID) {
const [isOnline, setIsOnline] = useState(null);
useEffect(() => {
function handleStatusChange(status) {
setIsOnline(status.isOnline);
}
ChatAPI.subscribeToFriendStatus(friendID, handleStatusChange);
return () => {
ChatAPI.unsubscribeFromFriendStatus(friendID,
handleStatusChange);
};
});

return isOnline;
}
import React from 'react';
import useFriendStatus from ‘./useFriendStatus’;
function FriendListItem(props) {
const isOnline = useFriendStatus(props.friend.id);
return (
<li style={{ color: isOnline ? 'green' : 'black' }}>
{props.friend.name}
</li>
);
}

Written by

Full-Stack Software Engineer, Designer, and salsa dancer.

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