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⚡ Bolt: Optimize dashboard clock performance #87

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⚡ Bolt: Optimize dashboard clock performance #87

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3 changes: 3 additions & 0 deletions .jules/bolt.md
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Original file line number Diff line number Diff line change
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## 2026-06-16 - [Dashboard Clock Optimization]
**Learning:** Re-verified that the dashboard clock was a significant bottleneck (~1.3ms per call) due to repeated `toLocaleTimeString` calls and DOM `innerHTML` parsing. Caching `Intl.DateTimeFormat` and DOM references provided a ~100x speedup.
**Action:** Always check high-frequency UI updates (like clocks) for redundant localization and DOM manipulation. Use IIFEs for clean caching.
76 changes: 51 additions & 25 deletions index.html
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Expand Up @@ -334,8 +334,17 @@ <h1>🌟 人生明燈</h1>
<div class="service-description">時區轉換和時間計算</div>
<div class="service-content">
<div class="weather-info">
<div id="currentTime"></div>
<div id="timeZones"></div>
<div id="currentTime">
<div id="local-time" class="temp"></div>
<div id="local-date"></div>
</div>
<div id="timeZones">
<small>
東京: <span id="tokyo-time"></span><br>
紐約: <span id="ny-time"></span><br>
倫敦: <span id="london-time"></span>
</small>
</div>
</div>
<button onclick="updateTime()">更新時間</button>
</div>
Expand Down Expand Up @@ -481,29 +490,46 @@ <h1>🌟 人生明燈</h1>
}

// 時間工具
function updateTime() {
const now = new Date();
const timeDiv = document.getElementById('currentTime');
const timeZonesDiv = document.getElementById('timeZones');

timeDiv.innerHTML = `
<div class="temp">${now.toLocaleTimeString('zh-TW')}</div>
<div>${now.toLocaleDateString('zh-TW', {
year: 'numeric',
month: 'long',
day: 'numeric',
weekday: 'long'
})}</div>
`;

timeZonesDiv.innerHTML = `
<small>
東京: ${now.toLocaleTimeString('ja-JP', {timeZone: 'Asia/Tokyo'})}<br>
紐約: ${now.toLocaleTimeString('en-US', {timeZone: 'America/New_York'})}<br>
倫敦: ${now.toLocaleTimeString('en-GB', {timeZone: 'Europe/London'})}
</small>
`;
}
const updateTime = (function() {
// 效能優化：快取 Intl.DateTimeFormat 實例和 DOM 元素引用
// Performance optimization: cache Intl.DateTimeFormat instances and DOM element references
let localTimeFmt, localDateFmt, tokyoFmt, nyFmt, londonFmt;
let localTimeEl, localDateEl, tokyoEl, nyEl, londonEl;
let lastDateStr = '';

return function() {
const now = new Date();

// 延遲初始化快取 (Lazy initialization of cache)
if (!localTimeFmt) {
localTimeFmt = new Intl.DateTimeFormat('zh-TW', { hour: 'numeric', minute: 'numeric', second: 'numeric' });
localDateFmt = new Intl.DateTimeFormat('zh-TW', { year: 'numeric', month: 'long', day: 'numeric', weekday: 'long' });
tokyoFmt = new Intl.DateTimeFormat('ja-JP', { timeZone: 'Asia/Tokyo', hour: 'numeric', minute: 'numeric', second: 'numeric' });
nyFmt = new Intl.DateTimeFormat('en-US', { timeZone: 'America/New_York', hour: 'numeric', minute: 'numeric', second: 'numeric' });
londonFmt = new Intl.DateTimeFormat('en-GB', { timeZone: 'Europe/London', hour: 'numeric', minute: 'numeric', second: 'numeric' });

localTimeEl = document.getElementById('local-time');
localDateEl = document.getElementById('local-date');
tokyoEl = document.getElementById('tokyo-time');
nyEl = document.getElementById('ny-time');
londonEl = document.getElementById('london-time');
}

// 更新時間 (Update time)
localTimeEl.textContent = localTimeFmt.format(now);
tokyoEl.textContent = tokyoFmt.format(now);
nyEl.textContent = nyFmt.format(now);
londonEl.textContent = londonFmt.format(now);

// Dirty-checking: 只有當日期改變時才更新日期 DOM
// Dirty-checking: only update date DOM when the date actually changes
const currentDateStr = now.toDateString();
if (currentDateStr !== lastDateStr) {
localDateEl.textContent = localDateFmt.format(now);
lastDateStr = currentDateStr;
}
};
})();

// 實用函數
function hexToRgb(hex) {
Expand Down