倒计时：可添加可删除的倒计时函数

html 复制代码
<!DOCTYPE html>
<html lang="zh-CN">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>倒计时</title>
</head>

<body>
    <!-- 倒计时 -->
    <div id="countdownContainer"></div>
</body>
<script>
    /* 添加倒计时函数*/
    (function () {
        // 初始化倒计时功能
        function initCountdown() {
            initUI();
            updateCountdowns();
            setInterval(updateCountdowns, 1000);
        }

        // 创建初始用户界面
        function initUI() {
            var container = document.createElement('div');
            container.id = 'countdownContainer';
            document.body.appendChild(container);

            var addButton = document.createElement("button");
            addButton.innerHTML = "添加倒计时";
            addButton.onclick = addCountdown;
            document.body.appendChild(addButton);
        }

        // 更新倒计时显示
        function updateCountdowns() {
            var container = document.getElementById("countdownContainer");
            container.innerHTML = "";
            var countdowns = getCountdowns();
            countdowns.forEach(function (countdown, index) {
                var div = document.createElement("div");
                div.innerHTML = `<strong>${countdown.title}</strong>: ${getTimeRemaining(countdown.date)} <button onclick="window.deleteCountdown(${index})">删除</button>`;
                container.appendChild(div);
            });
        }

        // 计算剩余时间
        function getTimeRemaining(endDate) {
            var total = Date.parse(endDate) - Date.parse(new Date());
            var seconds = Math.floor((total / 1000) % 60);
            var minutes = Math.floor((total / 1000 / 60) % 60);
            var hours = Math.floor((total / (1000 * 60 * 60)) % 24);
            var days = Math.floor(total / (1000 * 60 * 60 * 24));
            return `${days}天 ${padZero(hours)}小时 ${padZero(minutes)}分钟 ${padZero(seconds)}秒`;
        }

        // 为数字小于10的前面添加0
        function padZero(num) {
            return num < 10 ? `0${num}` : num;
        }

        // 添加新的倒计时
        function addCountdown() {
            var formContainer = document.createElement("div");
            formContainer.id = "countdownForm";
            formContainer.innerHTML = `
                <input type="text" id="countdownTitle" placeholder="提示信息">
                <input type="datetime-local" id="countdownDate">
                <button onclick="window.saveCountdown()">保存倒计时</button>
                <button onclick="window.cancelCountdown()">取消</button>
            `;
            document.body.appendChild(formContainer);
            formContainer.style.display = "block";
        }

        // 保存倒计时到LocalStorage
        window.saveCountdown = function() {
            var title = document.getElementById("countdownTitle").value;
            var date = document.getElementById("countdownDate").value;
            if (title && date) {
                var countdowns = getCountdowns();
                countdowns.push({ title: title, date: date });
                localStorage.setItem("countdowns", JSON.stringify(countdowns));
                document.getElementById("countdownForm").remove();
                updateCountdowns();
            }
        }

        // 删除指定的倒计时
        window.deleteCountdown = function(index) {
            var countdowns = getCountdowns();
            countdowns.splice(index, 1);
            localStorage.setItem("countdowns", JSON.stringify(countdowns));
            updateCountdowns();
        }

        // 取消倒计时的添加
        window.cancelCountdown = function() {
            document.getElementById("countdownForm").remove();
        }

        // 从LocalStorage获取倒计时
        function getCountdowns() {
            return JSON.parse(localStorage.getItem("countdowns")) || [];
        }

        // 启动倒计时功能
        window.onload = initCountdown;
    })();
    /* 添加倒计时函数 结束*/
</script>

</html>