this demo looks better with the following static css style

* { margin: 0; padding: 0; }
h1 { text-align: center; padding-block: 1em; }
main p { text-align: justify; }
footer p { text-align: center; }
p { padding: 1em; }

Simple Page

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export default function App() {
	return <>
		<Header />
		<Main />
		<Footer />
	</>;
}

function Header() {
	return <h1>
		Shahar Website
	</h1>;
}

function Main() {
	return <main>
		<Article />
		<Article />
		<Article />
	</main>;
}

function Article() {
	return <p>
		Lorem ipsum...
	</p>;
}

function Footer() {
	return <footer>
		<p>all rights reserved to me</p>
	</footer>;
}

Scattered Theme Switches

add theme “switch” for each component who will implement accordingly.

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export default function App() {
	return <>
		<Header />
		<Main />
		<Footer />
	</>;
}

function Header() {
	const isDark = false;

	return <h1>
		Shahar Website
	</h1>;
}

function Main() {
	return <main>
		<Article />
		<Article />
		<Article />
	</main>;
}

function Article() {
	const isDark = false;

	return <p>
		Lorem ipsum...
	</p>;
}

function Footer() {
	const isDark = false;

	return <footer>
		<p>all rights reserved to me</p>
	</footer>;
}

Conditional Style

add conditional styling implementation

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export default function App() {
	return <>
		<Header />
		<Main />
		<Footer />
	</>;
}

function Header() {
	const isDark = true;

	const style = isDark ?
		{ backgroundColor: 'black', color: 'white' } :
		{ backgroundColor: 'white', color: 'black' };

	return <h1 style={style}>
		Shahar Website
	</h1>;
}

function Main() {
	return <main>
		<Article />
		<Article />
		<Article />
	</main>;
}

function Article() {
	const isDark = true;

	const style = isDark ?
		{ backgroundColor: 'black', color: 'white' } :
		{ backgroundColor: 'white', color: 'black' };

	return <p style={style}>
		Lorem ipsum...
	</p>;
}

function Footer() {
	const isDark = true;

	const style = isDark ?
		{ backgroundColor: 'black', color: 'white' } :
		{ backgroundColor: 'white', color: 'black' };

	return <footer style={style}>
		<p>all rights reserved to me</p>
	</footer>;
}

Centralize

We would like to centralize the theme.

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export default function App() {
	const isDark = false; // one to rule them all

	return <>
		<Header isDark={isDark} />
		<Main isDark={isDark} />
		<Footer isDark={isDark} />
	</>;
}

Prop Drilling

we will use props

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export default function App() {
	const isDark = false; // one to rule them all

	return <>
		<Header isDark={isDark} />
		<Main isDark={isDark} />
		<Footer isDark={isDark} />
	</>;
}

function Header({ isDark }) {
	const style = isDark ?
		{ backgroundColor: 'black', color: 'white' } :
		{ backgroundColor: 'white', color: 'black' };

	return <h1 style={style}>
		Shahar Website
	</h1>;
}

function Main({ isDark }) {
	return <main>
		<Article isDark={isDark} />
		<Article isDark={isDark} />
		<Article isDark={isDark} />
	</main>;
}

function Article({ isDark }) {
	const style = isDark ?
		{ backgroundColor: 'black', color: 'white' } :
		{ backgroundColor: 'white', color: 'black' };

	return <p style={style}>
		Lorem ipsum...
	</p>;
}

function Footer({ isDark }) {
	const style = isDark ?
		{ backgroundColor: 'black', color: 'white' } :
		{ backgroundColor: 'white', color: 'black' };

	return <footer style={style}>
		<p>all rights reserved to me</p>
	</footer>;
}

so tidious!

Let’s Use Context

create context object

import { createContext } from "react";
const ThemeContext = createContext(null);

the null arg determine a default value we will see.

wrap the app with ThemeContext.Provider component and pass to it’s value prop the data we used to “drill” before

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export default function App() {
	const isDark = false;

	return <>
		<ThemeContext.Provider value={isDark}>
			<Header />
			<Main />
			<Footer />
		</ThemeContext.Provider>
	</>;
}

Use The Context

import the hook

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import {
	createContext,
	useContext
} from "react";

run this hook in the beginning of every component that actualy use it

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function Header() {
	const isDark = useContext(ThemeContext);

	const style = isDark ?
		{ backgroundColor: 'black', color: 'white' } :
		{ backgroundColor: 'white', color: 'black' };

	return <h1 style={style}>
		Shahar Website
	</h1>;
}

function Main() {
	return <main>
		<Article />
		<Article />
		<Article />
	</main>;
}

function Article() {
	const isDark = useContext(ThemeContext);

	const style = isDark ?
		{ backgroundColor: 'black', color: 'white' } :
		{ backgroundColor: 'white', color: 'black' };

	return <p style={style}>
		Lorem ipsum...
	</p>;
}

function Footer() {
	const isDark = useContext(ThemeContext);

	const style = isDark ?
		{ backgroundColor: 'black', color: 'white' } :
		{ backgroundColor: 'white', color: 'black' };

	return <footer style={style}>
		<p>all rights reserved to me</p>
	</footer>;
}

Custom Hook

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import { useContext, createContext } from "react";

const ThemeContext = createContext(null);

export function ThemeProvider({ children, value }) {
    return <ThemeContext.Provider value={value}>
        {children}
    </ThemeContext.Provider>;
}

export function useTheme() {
    return useContext(ThemeContext);
}

Use Our Custom Hook

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import { useTheme, ThemeProvider } from "./Theme";

export default function App() {
	const isDark = true;

	return <>
		<ThemeProvider value={isDark}>
			<Header />
			<Main />
			<Footer />
		</ThemeProvider>
	</>;
}

function Header() {
	const isDark = useTheme();

	const style = isDark ?
		{ backgroundColor: 'black', color: 'white' } :
		{ backgroundColor: 'white', color: 'black' };

	return <h1 style={style}>
		Shahar Website
	</h1>;
}

function Main() {
	return <main>
		<Article />
		<Article />
		<Article />
	</main>;
}

function Article() {
	const isDark = useTheme();

	const style = isDark ?
		{ backgroundColor: 'black', color: 'white' } :
		{ backgroundColor: 'white', color: 'black' };

	return <p style={style}>
		Lorem ipsum dolor sit amet,
		consectetur adipiscing elit,
		sed do eiusmod tempor incididunt
		ut labore et dolore magna aliqua.
	</p>;
}

function Footer() {
	const isDark = useTheme();

	const style = isDark ?
		{ backgroundColor: 'black', color: 'white' } :
		{ backgroundColor: 'white', color: 'black' };

	return <footer style={style}>
		<p>all rights reserved to me</p>
	</footer>;
}

Simple Page#

Scattered Theme Switches#

Conditional Style#

Centralize#

Prop Drilling#

Let’s Use Context#

Use The Context#

Custom Hook#

Use Our Custom Hook#