Convert UTC Milliseconds to Local Time Javascript

   <div class="container">
          <h1>UTC Milliseconds Converter</h1>
          <p class="subtitle">Convert UTC milliseconds to local time</p>

          <div class="input-group">
              <label for="milliseconds">Enter UTC Milliseconds</label>
              <input 
                  type="text" 
                  id="milliseconds" 
                  placeholder="e.g., 1730822400000"
                  value="1730822400000"
              >
          </div>

          <div class="button-group">
              <button onclick="convertTime()">Convert</button>
              <button class="secondary-btn" onclick="useCurrentTime()">Use Current Time</button>
          </div>

          <div class="result-box" id="resultBox">
              <div class="result-item">
                  <div class="result-label">Local Date & Time</div>
                  <div class="result-value" id="localDateTime">-</div>
              </div>
              <div class="result-item">
                  <div class="result-label">ISO String</div>
                  <div class="result-value" id="isoString">-</div>
              </div>
              <div class="result-item">
                  <div class="result-label">UTC String</div>
                  <div class="result-value" id="utcString">-</div>
              </div>
          </div>

          <div class="example">
              Example: Current time is <span id="currentMs"></span> ms
          </div>
      </div>

   * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            min-height: 100vh;
            display: flex;
            align-items: center;
            justify-content: center;
            padding: 20px;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
        }

        .container {
            background: rgba(255, 255, 255, 0.95);
            padding: 40px;
            border-radius: 16px;
            box-shadow: 0 20px 60px rgba(0, 0, 0, 0.15);
            max-width: 500px;
            width: 100%;
        }

        h1 {
            font-size: 24px;
            color: #333;
            margin-bottom: 10px;
            text-align: center;
        }

        .subtitle {
            text-align: center;
            color: #666;
            font-size: 14px;
            margin-bottom: 30px;
        }

        .input-group {
            margin-bottom: 25px;
        }

        label {
            display: block;
            font-size: 14px;
            color: #555;
            margin-bottom: 8px;
            font-weight: 500;
        }

        input {
            width: 100%;
            padding: 14px;
            border: 2px solid #e0e0e0;
            border-radius: 8px;
            font-size: 16px;
            transition: border-color 0.3s;
            font-family: 'Courier New', monospace;
        }

        input:focus {
            outline: none;
            border-color: #667eea;
        }

        .button-group {
            display: flex;
            gap: 10px;
            margin-bottom: 25px;
        }

        button {
            flex: 1;
            padding: 14px;
            border: none;
            border-radius: 8px;
            font-size: 15px;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s;
            color: white;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
        }

        button:hover {
            transform: translateY(-2px);
            box-shadow: 0 6px 20px rgba(0, 0, 0, 0.2);
        }

        button:active {
            transform: translateY(0);
        }

        .secondary-btn {
            background: linear-gradient(135deg, #764ba2 0%, #667eea 100%) !important;
        }

        .result-box {
            background: #f8f9fa;
            padding: 20px;
            border-radius: 8px;
            border-left: 4px solid #667eea;
        }

        .result-item {
            margin-bottom: 15px;
        }

        .result-item:last-child {
            margin-bottom: 0;
        }

        .result-label {
            font-size: 12px;
            color: #888;
            text-transform: uppercase;
            letter-spacing: 0.5px;
            margin-bottom: 5px;
        }

        .result-value {
            font-size: 16px;
            color: #333;
            font-weight: 500;
            font-family: 'Courier New', monospace;
        }

        .example {
            text-align: center;
            margin-top: 20px;
            font-size: 13px;
            color: #999;
        }

     function convertTime() {
            const input = document.getElementById('milliseconds').value.trim();
            const ms = parseInt(input);

            if (isNaN(ms)) {
                alert('Please enter a valid number');
                return;
            }

            const date = new Date(ms);

            // Local date and time
            const localDateTime = date.toLocaleString('en-US', {
                weekday: 'short',
                year: 'numeric',
                month: 'short',
                day: 'numeric',
                hour: '2-digit',
                minute: '2-digit',
                second: '2-digit',
                hour12: true
            });

            document.getElementById('localDateTime').textContent = localDateTime;
            document.getElementById('isoString').textContent = date.toISOString();
            document.getElementById('utcString').textContent = date.toUTCString();
        }

        function useCurrentTime() {
            const now = Date.now();
            document.getElementById('milliseconds').value = now;
            convertTime();
        }

        function updateCurrentMs() {
            document.getElementById('currentMs').textContent = Date.now().toLocaleString();
        }

        // Initialize
        updateCurrentMs();
        setInterval(updateCurrentMs, 1000);
        convertTime();

        // Allow Enter key to convert
        document.getElementById('milliseconds').addEventListener('keypress', function(e) {
            if (e.key === 'Enter') {
                convertTime();
            }
        });