feat: enhance date and time display with Chinese format; add search engine switcher

- Updated dateTime function to display date and time in Chinese format.
- Introduced setSearchEngine function to switch between Google and Baidu as search engines.
- Added event listener for search engine switching on click.
- Persisted selected search engine in localStorage for user preference.
- Changed weatherBalloon city ID to Beijing, China.

js/main.js

@@ -1,7 +1,23 @@
 function dateTime() {
 	const date = new Date();
-	let today = date.toDateString();
-	let time = date.toLocaleTimeString();
+	
+	// 中文日期格式
+	const year = date.getFullYear();
+	const month = date.getMonth() + 1;
+	const day = date.getDate();
+	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[date.getDay()];
+	
+	const today = `${year}年${month}月${day}日 ${weekDay}`;
+	
+	// 中文时间格式
+	const time = date.toLocaleTimeString('zh-CN', {
+		hour12: false,
+		hour: '2-digit',
+		minute: '2-digit',
+		second: '2-digit'
+	});
+	
 	document.getElementById('date-time').innerHTML = '<p id="date">' + today + '</p><p id="time">' + time + '</p>';
 	setTimeout(dateTime, 1000);
 }
@@ -21,7 +37,61 @@ function weatherBalloon(cityID) {
 		});
 }
 
+function setSearchEngine(engine) {
+	const searchForm = document.getElementById('search-form');
+	const searchInput = document.getElementById('search-input');
+	const searchEngineSelector = document.getElementById('search-engine-selector');
+	const baiduIcon = searchEngineSelector?.querySelector('.baidu-icon');
+	const googleIcon = searchEngineSelector?.querySelector('.google-icon');
+
+	if (!searchForm || !searchInput || !searchEngineSelector || !baiduIcon || !googleIcon) {
+		return;
+	}
+
+	if (engine === 'google') {
+		searchEngineSelector.dataset.engine = 'google';
+		searchEngineSelector.setAttribute('aria-label', '当前搜索引擎：Google，点击切换至 Baidu');
+		searchEngineSelector.setAttribute('title', '当前：Google（点击切换至 Baidu）');
+		searchForm.action = 'https://www.google.com/search';
+		searchInput.name = 'q';
+		baiduIcon.style.display = 'none';
+		googleIcon.style.display = 'block';
+	} else {
+		searchEngineSelector.dataset.engine = 'baidu';
+		searchEngineSelector.setAttribute('aria-label', '当前搜索引擎：Baidu，点击切换至 Google');
+		searchEngineSelector.setAttribute('title', '当前：Baidu（点击切换至 Google）');
+		searchForm.action = 'https://www.baidu.com/s';
+		searchInput.name = 'wd';
+		baiduIcon.style.display = 'block';
+		googleIcon.style.display = 'none';
+	}
+
+	try {
+		localStorage.setItem('searchEngine', searchEngineSelector.dataset.engine);
+	} catch (error) {
+		// Ignore storage errors (e.g., disabled storage)
+	}
+	searchInput.focus();
+}
+
+function switchSearchEngine() {
+	const searchEngineSelector = document.getElementById('search-engine-selector');
+	const nextEngine = (searchEngineSelector?.dataset.engine || 'baidu') === 'baidu' ? 'google' : 'baidu';
+	setSearchEngine(nextEngine);
+}
+
 function traichu() {
 	dateTime();
-	weatherBalloon(1850147); //OpenWeather city ID
+	weatherBalloon(1816670); //OpenWeather city ID - Beijing, China
+    const selector = document.getElementById('search-engine-selector');
+    if (selector) {
+		selector.addEventListener('click', switchSearchEngine);
+		let savedEngine = null;
+		try {
+			savedEngine = localStorage.getItem('searchEngine');
+		} catch (error) {
+			savedEngine = null;
+		}
+		setSearchEngine(savedEngine === 'google' ? 'google' : 'baidu');
+	}
 }