Interruttore dei temi scuro e chiaro

Questo pattern mostra come creare un interruttore per il tuo sito web che consenta di passare dal tema chiaro al tema scuro e salvare la preferenza per le visite successive.

Articolo completo · Video su YouTube · Fonte su GitHub

<button class="theme-toggle" id="theme-toggle" title="Toggles light & dark" aria-label="auto" aria-live="polite">
 
<svg class="sun-and-moon" aria-hidden="true" width="24" height="24" viewBox="0 0 24 24">
   
<mask class="moon" id="moon-mask">
     
<rect x="0" y="0" width="100%" height="100%" fill="white" />
     
<circle cx="24" cy="10" r="6" fill="black" />
   
</mask>
   
<circle class="sun" cx="12" cy="12" r="6" mask="url(#moon-mask)" fill="currentColor" />
   
<g class="sun-beams" stroke="currentColor">
     
<line x1="12" y1="1" x2="12" y2="3" />
     
<line x1="12" y1="21" x2="12" y2="23" />
     
<line x1="4.22" y1="4.22" x2="5.64" y2="5.64" />
     
<line x1="18.36" y1="18.36" x2="19.78" y2="19.78" />
     
<line x1="1" y1="12" x2="3" y2="12" />
     
<line x1="21" y1="12" x2="23" y2="12" />
     
<line x1="4.22" y1="19.78" x2="5.64" y2="18.36" />
     
<line x1="18.36" y1="5.64" x2="19.78" y2="4.22" />
     
</g>
 
</svg>
</button>

       
@import "https://unpkg.com/open-props/easings.min.css";

.sun-and-moon > :is(.moon, .sun, .sun-beams) {
 
transform-origin: center;
}

.sun-and-moon > :is(.moon, .sun) {
 
fill: var(--icon-fill);
}

.theme-toggle:is(:hover, :focus-visible) > .sun-and-moon > :is(.moon, .sun) {
 
fill: var(--icon-fill-hover);
}

.sun-and-moon > .sun-beams {
 
stroke: var(--icon-fill);
 
stroke-width: 2px;
}

.theme-toggle:is(:hover, :focus-visible) .sun-and-moon > .sun-beams {
 
stroke: var(--icon-fill-hover);
}

[data-theme="dark"] .sun-and-moon > .sun {
 
transform: scale(1.75);
}

[data-theme="dark"] .sun-and-moon > .sun-beams {
 
opacity: 0;
}

[data-theme="dark"] .sun-and-moon > .moon > circle {
 
transform: translateX(-7px);
}

@supports (cx: 1) {
 
[data-theme="dark"] .sun-and-moon > .moon > circle {
   
cx: 17;
   
transform: translateX(0);
 
}
}

@media (prefers-reduced-motion: no-preference) {
 
.sun-and-moon > .sun {
   
transition: transform .5s var(--ease-elastic-3);
 
}

 
.sun-and-moon > .sun-beams {
   
transition: transform .5s var(--ease-elastic-4), opacity .5s var(--ease-3);
 
}

 
.sun-and-moon .moon > circle {
   
transition: transform .25s var(--ease-out-5);
 
}

 
@supports (cx: 1) {
   
.sun-and-moon .moon > circle {
     
transition: cx .25s var(--ease-out-5);
   
}
 
}

 
[data-theme="dark"] .sun-and-moon > .sun {
   
transition-timing-function: var(--ease-3);
   
transition-duration: .25s;
   
transform: scale(1.75);
 
}

 
[data-theme="dark"] .sun-and-moon > .sun-beams {
   
transition-duration: .15s;
   
transform: rotateZ(-25deg);
 
}

 
[data-theme="dark"] .sun-and-moon > .moon > circle {
   
transition-duration: .5s;
   
transition-delay: .25s;
 
}
}
       

       
const storageKey = 'theme-preference'

const onClick = () => {
 
// flip current value
  theme
.value = theme.value === 'light'
   
? 'dark'
   
: 'light'

  setPreference
()
}

const getColorPreference = () => {
 
if (localStorage.getItem(storageKey))
   
return localStorage.getItem(storageKey)
 
else
   
return window.matchMedia('(prefers-color-scheme: dark)').matches
     
? 'dark'
     
: 'light'
}

const setPreference = () => {
  localStorage
.setItem(storageKey, theme.value)
  reflectPreference
()
}

const reflectPreference = () => {
  document
.firstElementChild
   
.setAttribute('data-theme', theme.value)

  document
   
.querySelector('#theme-toggle')
   
?.setAttribute('aria-label', theme.value)
}

const theme = {
  value
: getColorPreference(),
}

// set early so no page flashes / CSS is made aware
reflectPreference
()

window
.onload = () => {
 
// set on load so screen readers can see latest value on the button
  reflectPreference
()

 
// now this script can find and listen for clicks on the control
  document
   
.querySelector('#theme-toggle')
   
.addEventListener('click', onClick)
}

// sync with system changes
window
 
.matchMedia('(prefers-color-scheme: dark)')
 
.addEventListener('change', ({matches:isDark}) => {
    theme
.value = isDark ? 'dark' : 'light'
    setPreference
()
 
})