实时时钟

let is24Hour = true;
let showSeconds = true;

function updateClock() {
    const now = new Date();
    let hours = now.getHours();
    const minutes = now.getMinutes();
    const seconds = now.getSeconds();

    // 12小时制转换
    if (!is24Hour) {
        const period = hours >= 12 ? ' PM' : ' AM';
        hours = hours % 12 || 12;
        return `${pad(hours)}:${pad(minutes)}${showSeconds ? ':' + pad(seconds) : ''}${period}`;
    }

    // 24小时制
    return `${pad(hours)}:${pad(minutes)}${showSeconds ? ':' + pad(seconds) : ''}`;
}

function pad(num) {
    return num.toString().padStart(2, '0');
}

function formatDate() {
    const now = new Date();
    const weekdays = ['星期日', '星期一', '星期二', '星期三', '星期四', '星期五', '星期六'];
    const weekday = weekdays[now.getDay()];

    return `${now.getFullYear()}年${now.getMonth() + 1}月${now.getDate()}日 ${weekday}`;
}