var now = new Date(); // 創(chuàng)建一個表示當(dāng)前時間的對象

var now = new Date();

console.log("年：" + now.getFullYear());
console.log("月：" + (now.getMonth() + 1)); // 加 1
console.log("日：" + now.getDate());
console.log("時：" + now.getHours());
console.log("分：" + now.getMinutes());
console.log("秒：" + now.getSeconds());
console.log("星期：" + now.getDay());

<style>
.time span {
    display: inline-block;
    width: 40px;
    height: 20px;
}
</style>

<div class="time">
    當(dāng)前時間：<br><br>
    <span id="year"></span>年
    <span id="month"></span>月
    <span id="day"></span>日
    <span id="hour"></span>時
    <span id="minute"></span>分
    <span id="second"></span>秒
</div>

function showTime() {
    var now = new Date();

    var year = now.getFullYear();
    var month = now.getMonth() + 1; // 注意加 1
    var day = now.getDate();
    var hour = now.getHours();
    var minute = now.getMinutes();
    var second = now.getSeconds();

    // 更新頁面內(nèi)容
    document.getElementById("year").innerHTML = year;
    document.getElementById("month").innerHTML = month;
    document.getElementById("day").innerHTML = day;
    document.getElementById("hour").innerHTML = hour;
    document.getElementById("minute").innerHTML = minute;
    document.getElementById("second").innerHTML = second;
}

// 初始調(diào)用一次
showTime();

// 每隔 1 秒更新一次時間
setInterval(showTime, 1000);

<div id="clock"></div>

function updateTime() {
    var date = new Date();

    var year = date.getFullYear();
    var month = date.getMonth() + 1;
    var day = date.getDate();
    var hours = date.getHours();
    var minutes = date.getMinutes();
    var seconds = date.getSeconds();

    var week = ["星期日", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六"];
    var currentWeek = week[date.getDay()];

    // 格式化為統(tǒng)一格式
    var timeStr = `${year}年${month}月${day}日 ${hours}:${minutes}:${seconds} ${currentWeek}`;

    document.getElementById("clock").innerText = timeStr;
}

updateTime();
setInterval(updateTime, 1000);