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mirror of https://github.com/jakejarvis/jarv.is.git synced 2025-04-27 13:56:22 -04:00
jarv.is/assets/js/dark-mode.js
2020-05-04 21:25:07 -04:00

84 lines
2.7 KiB
JavaScript

/* jshint esversion: 6, indent: 2, browser: true, quotmark: single */
/*! Dark mode switcheroo | MIT License | jrvs.io/darkmode */
(function () {
// improve variable mangling when minifying
var win = window;
var doc = win.document;
var body = doc.body;
var classes = body.classList;
var storage = localStorage;
// check for preset `dark_mode_pref` preference in local storage
var pref_key = 'dark_mode_pref';
var pref = storage.getItem(pref_key);
// change CSS via these <body> classes:
var dark = 'dark';
var light = 'light';
// which class is <body> set to initially?
var default_theme = light;
// use an element with class `dark-mode-toggle` to trigger swap when clicked
var toggle = doc.querySelector('.dark-mode-toggle');
// keep track of current state no matter how we got there
var active = (default_theme === dark);
// receives a class name and switches <body> to it
var activateTheme = function (theme) {
classes.remove(dark, light);
classes.add(theme);
active = (theme === dark);
};
// if user already explicitly toggled in the past, restore their preference
if (pref === dark) activateTheme(dark);
if (pref === light) activateTheme(light);
// user has never clicked the button, so go by their OS preference until/if they do so
if (!pref) {
// returns media query selector syntax
var prefers = function (theme) {
return '(prefers-color-scheme: ' + theme + ')';
};
// check for OS dark/light mode preference and switch accordingly
// default to `default_theme` set above if unsupported
if (win.matchMedia(prefers(dark)).matches)
activateTheme(dark);
else if (win.matchMedia(prefers(light)).matches)
activateTheme(light);
else
activateTheme(default_theme);
// real-time switching if supported by OS/browser
win.matchMedia(prefers(dark)).addListener(function (e) { if (e.matches) activateTheme(dark); });
win.matchMedia(prefers(light)).addListener(function (e) { if (e.matches) activateTheme(light); });
}
// don't freak out if page happens not to have a toggle
if (toggle) {
// toggle re-appears now that we know user has JS enabled
toggle.style.visibility = 'visible';
// handle toggle click
toggle.addEventListener('click', function () {
// switch to the opposite theme & save preference in local storage
if (active) {
activateTheme(light);
storage.setItem(pref_key, light);
// send event to SA
sa_event('triggered_light_mode');
} else {
activateTheme(dark);
storage.setItem(pref_key, dark);
// send event to SA
sa_event('triggered_dark_mode');
}
}, true);
}
})();