本文在Typecho下实装
新建darkmode.js文件

//点击启用
function switchdarkmodeMode(){
    var darkmode = document.cookie.replace(/(?:(?:^|.*;\s*)darkmode\s*\=\s*([^;]*).*$)|^.*$/, "$1") || '0';
    if(darkmode == '0'){
        document.body.classList.add('darkmode');
        document.cookie = "darkmode=1;path=/"
        console.log('夜间模式开启');
    }else{
        document.body.classList.remove('darkmode');
        document.cookie = "darkmode=0;path=/"
        console.log('夜间模式关闭');
    }
}
//22-7时间段自动启用
(function(){
    if(document.cookie.replace(/(?:(?:^|.*;\s*)darkmode\s*\=\s*([^;]*).*$)|^.*$/, "$1") === ''){
        if(new Date().getHours() > 22 || new Date().getHours() < 7){
            document.body.classList.add('darkmode');
            document.cookie = "darkmode=1;path=/";
            console.log('夜间模式开启');
        }else{
            document.body.classList.remove('darkmode');
            document.cookie = "darkmode=0;path=/";
            console.log('夜间模式关闭');
        }
    }else{
        var darkmode = document.cookie.replace(/(?:(?:^|.*;\s*)darkmode\s*\=\s*([^;]*).*$)|^.*$/, "$1") || '0';
        if(darkmode == '0'){
            document.body.classList.remove('darkmode');
        }else if(darkmode == '1'){
            document.body.classList.add('darkmode');
        }
    }
})();

页面头部调用深色css

<link rel="stylesheet" href="'.theurl.'css/darkmode.css" type="text/css" />

页脚调用js

<script type="text/javascript" src="'.theurl.'js/darkmode.js"></script>

新建darkmode.css文件
深色样式格式

.darkmode XXX

手动检查

<a href="javascript:switchdarkmodeMode()">Dark Mode</a>