toggle: The clickable HTML element used to toggle between the two themes. (optional, default: null)
classes: An object containing the <body> class names for the light and dark themes. (optional, default: { light: "light", dark: "dark" })
default: The initial <body> class hard-coded into the HTML template. (optional, default: "light")
storageKey: Name of the localStorage key holding the user's preference. (optional, default: "dark_mode_pref")

Browser

<button class="dark-mode-toggle">💡 Click to see the light... or not.</button>

<script src="https://unpkg.com/@jakejarvis/dark-mode/dist/index.js"></script>
<script>
  window.darkMode({
    toggle: document.querySelector(".dark-mode-toggle"),
    classes: {
      light: "light",
      dark: "dark",
    },
    default: "light",
    storageKey: "dark_mode_pref",
  });
</script>

Node

npm install @jakejarvis/dark-mode
# or...
yarn add @jakejarvis/dark-mode

import darkMode from "@jakejarvis/dark-mode";
// or:
// const darkMode = require("@jakejarvis/dark-mode");

darkMode({
  toggle: document.querySelector(".dark-mode-toggle"),
  classes: {
    light: "light",
    dark: "dark",
  },
  default: "light",
  storageKey: "dark_mode_pref",
});

License

MIT