Darkmode

    function loadTheme() {
        
        var theme = localStorage.getItem('theme');
        var dataTheme = localStorage.getItem('theme');
    
        if(dataTheme === 'dark') {
            document.getElementById('light-theme').setAttribute('href', "./app/style/dark.css");
        } else {
            document.getElementById('light-theme').setAttribute('href', "./app/style/light.css");
        } 
        
    }
    

    function toggleDarkMode() {
    
        var theme = localStorage.getItem('theme');
        var dataTheme = localStorage.getItem('theme');
    
        if(dataTheme === 'dark') {
            localStorage.setItem("theme", "light");
            document.getElementById('light-theme').setAttribute('href', "./app/style/light.css");
        } else {
            localStorage.setItem("theme", "dark");
            document.getElementById('light-theme').setAttribute('href', "./app/style/dark.css");
        }
        
    }
    

    function toggleTheme(toggleSheet){
        document.getElementById('light-theme').setAttribute('href', toggleSheet);  
    }
    

    function swapTheme(){
       let currentTheme = document.getElementById('light-theme').getAttribute('href');
       if(currentTheme == "./app/style/light.css")
           document.getElementById('light-theme').setAttribute('href', "./app/style/dark.css");
       else
           document.getElementById('light-theme').setAttribute('href', "./app/style/light.css");
    }
    

Reference: