Dark mode in React and Tailwind in 3 simple steps

Getting a fully functional dark mode is super easy with Tailwind.

First, add this to your tailwind.config.js file:

module.exports = {
  ...
  darkMode: "class",
};

Then add global light/dark styles to your index stylesheet in your app: (hint: put this in the same file where you have the @tailwind base config, if you are using next.js, it's the stylesheet being imported in _app.jsx and for create-react-app index.js)

@tailwind base;
@tailwind components;
@tailwind utilities;

@layer base {
  body {
    @apply bg-white dark:bg-slate-800 text-black dark:text-white;
  }
}

Now for the fun part, let's implement the logic and a toggle button looking like this:

If you just want to skip to the final code, click here

Let's create a new component called DarkmodeSwitch:

export function DarkmodeSwitch() {
  const [isDarkMode, setIsDarkMode] = useState(false);
  return <button>{isDarkMode ? "Dark mode" : "Light mode"}</button>;
}

Add an onClick handler to toggle between the modes, let's also store it in localStorage for later.

const handleClick = () => {
  if (isDarkMode) {
    window.document.documentElement.classList.remove("dark");
    localStorage.setItem("theme", "light");
  } else {
    localStorage.setItem("theme", "dark");
    window.document.documentElement.classList.add("dark");
  }
  setIsDarkMode(!isDarkMode);
};

Add an useEffect to initially check what our users stored preference is:

useEffect(() => {
  const theme = localStorage.getItem("theme");
  if (theme === "dark") {
    window.document.documentElement.classList.add("dark");
    setIsDarkMode(true);
  }
}, []);

Finally let's add some cool icons and styling, and we get our finished code:

Full code

import { useEffect, useState } from "react";

const Moon = () => (
  <svg
    xmlns="http://www.w3.org/2000/svg"
    className="h-5 w-5"
    viewBox="0 0 20 20"
    fill="currentColor"
  >
    <path d="M17.293 13.293A8 8 0 016.707 2.707a8.001 8.001 0 1010.586 10.586z" />
  </svg>
);

const Sun = () => (
  <svg
    xmlns="http://www.w3.org/2000/svg"
    className="h-5 w-5"
    viewBox="0 0 20 20"
    fill="currentColor"
  >
    <path
      fillRule="evenodd"
      d="M10 2a1 1 0 011 1v1a1 1 0 11-2 0V3a1 1 0 011-1zm4 8a4 4 0 11-8 0 4 4 0 018 0zm-.464 4.95l.707.707a1 1 0 001.414-1.414l-.707-.707a1 1 0 00-1.414 1.414zm2.12-10.607a1 1 0 010 1.414l-.706.707a1 1 0 11-1.414-1.414l.707-.707a1 1 0 011.414 0zM17 11a1 1 0 100-2h-1a1 1 0 100 2h1zm-7 4a1 1 0 011 1v1a1 1 0 11-2 0v-1a1 1 0 011-1zM5.05 6.464A1 1 0 106.465 5.05l-.708-.707a1 1 0 00-1.414 1.414l.707.707zm1.414 8.486l-.707.707a1 1 0 01-1.414-1.414l.707-.707a1 1 0 011.414 1.414zM4 11a1 1 0 100-2H3a1 1 0 000 2h1z"
      clipRule="evenodd"
    />
  </svg>
);

export function DarkmodeSwitch() {
  const [isDarkMode, setIsDarkMode] = useState(false);

  useEffect(() => {
    const theme = localStorage.getItem("theme");
    if (theme === "dark") {
      window.document.documentElement.classList.add("dark");
      setIsDarkMode(true);
    }
  }, []);

  const handleClick = () => {
    if (isDarkMode) {
      window.document.documentElement.classList.remove("dark");
      localStorage.setItem("theme", "light");
    } else {
      localStorage.setItem("theme", "dark");
      window.document.documentElement.classList.add("dark");
    }
    setIsDarkMode(!isDarkMode);
  };

  return (
    <button
      className="text-gray-400 hover:bg-slate-200 p-2 flex items-center justify-center rounded-md dark:hover:bg-slate-700"
      onClick={handleClick}
      aria-label={`Toggle ${isDarkMode ? "light" : "dark"} mode`}
    >
      {isDarkMode ? <Sun /> : <Moon />}
    </button>
  );
}

The source code can also be found here

Wrapping up

Thats it! We could improve this further by on default use the preferred browser theme, and also avoiding a flash of light if using SSG/SRR, but this should get you pretty far for now. I also recommend this brilliant post by joshwcomeu