Switches daisyui theme (body:data-theme). Optionally, it will follow user's media-preference, and persists their choice.

example.jsx

import { component$ } from '@builder.io/qwik'
import ThemeSelect from '~/components/ThemeSelect'

export default component$(() => {
  return (
    <>
      HELLO
      <ThemeSelect useDarkPref themeDark='night' themeLight='winter'></ThemeSelect>
      <div class='p-2 bg-blue-200 dark:bg-red-500'>This is blue on light, and red on dark.</div>
    </>
  )
})

global.css

@import 'tailwindcss';

@plugin "daisyui" {
  themes:
    winter --default,
    night;
}

/* this makes tailwind's dark: work */
@custom-variant dark (body[data-theme="night"] &);

ThemeSelect.jsx

import { component$, useSignal, useVisibleTask$ } from '@builder.io/qwik'

// switches daisyui theme (body:data-theme)
// optionally, it will follow user's media-preference, and persists their choice

export default component$(({ themeDark = 'dark', themeLight = 'light', useDarkPref }) => {
  const theme = useSignal(true)
  useVisibleTask$(() => {
    if (localStorage.theme) {
      document.body.dataset.theme = localStorage.theme
    } else {
      if (useDarkPref) {
        document.body.dataset.theme = window.matchMedia && window.matchMedia('(prefers-color-scheme: dark)').matches ? themeDark : themeLight
      }
    }
    theme.value = document.body.dataset.theme === themeLight
  })
  return (
    <label class='swap swap-rotate'>
      <input type='checkbox' class='theme-controller' value='night' bind:checked={theme} onClick$={() => (localStorage.theme = document.body.dataset.theme = theme.value ? themeDark : themeLight)} />
      <svg class='swap-off h-10 w-10 fill-current' xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'>
        <path d='M5.64,17l-.71.71a1,1,0,0,0,0,1.41,1,1,0,0,0,1.41,0l.71-.71A1,1,0,0,0,5.64,17ZM5,12a1,1,0,0,0-1-1H3a1,1,0,0,0,0,2H4A1,1,0,0,0,5,12Zm7-7a1,1,0,0,0,1-1V3a1,1,0,0,0-2,0V4A1,1,0,0,0,12,5ZM5.64,7.05a1,1,0,0,0,.7.29,1,1,0,0,0,.71-.29,1,1,0,0,0,0-1.41l-.71-.71A1,1,0,0,0,4.93,6.34Zm12,.29a1,1,0,0,0,.7-.29l.71-.71a1,1,0,1,0-1.41-1.41L17,5.64a1,1,0,0,0,0,1.41A1,1,0,0,0,17.66,7.34ZM21,11H20a1,1,0,0,0,0,2h1a1,1,0,0,0,0-2Zm-9,8a1,1,0,0,0-1,1v1a1,1,0,0,0,2,0V20A1,1,0,0,0,12,19ZM18.36,17A1,1,0,0,0,17,18.36l.71.71a1,1,0,0,0,1.41,0,1,1,0,0,0,0-1.41ZM12,6.5A5.5,5.5,0,1,0,17.5,12,5.51,5.51,0,0,0,12,6.5Zm0,9A3.5,3.5,0,1,1,15.5,12,3.5,3.5,0,0,1,12,15.5Z' />
      </svg>
      <svg class='swap-on h-10 w-10 fill-current' xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'>
        <path d='M21.64,13a1,1,0,0,0-1.05-.14,8.05,8.05,0,0,1-3.37.73A8.15,8.15,0,0,1,9.08,5.49a8.59,8.59,0,0,1,.25-2A1,1,0,0,0,8,2.36,10.14,10.14,0,1,0,22,14.05,1,1,0,0,0,21.64,13Zm-9.5,6.69A8.14,8.14,0,0,1,7.08,5.22v.27A10.15,10.15,0,0,0,17.22,15.63a9.79,9.79,0,0,0,2.1-.22A8.11,8.11,0,0,1,12.14,19.73Z' />
      </svg>
    </label>
  )
})