apps/web/src/utils/sparkline.ts

@@ -9,5 +9,5 @@ export function sparkline(values: number[], width = 120, height = 32): string {
     const y = height - ((v - min) / range) * (height - 4) - 2;
     return `${x},${y}`;
   }).join(' ');
-  return `<svg width="${width}" height="${height}" class="inline-block" data-vals="${values.join(',')}"><polyline points="${points}" fill="none" stroke="#60a5fa" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round"/></svg>`;
+  return `<svg width="${width}" height="${height}" class="inline-block"><polyline points="${points}" fill="none" stroke="#60a5fa" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round"/></svg>`;
 }

apps/web/src/views/home.ejs

@@ -75,7 +75,43 @@
       } catch {}
     }, 30000);
 
-    // SSE: on each ping, update text fields and redraw sparkline in place
+    // Client-side sparkline — seed with SSR data, update locally on SSE
+    const _sparkData = {
+      <% it.monitors.forEach(function(m, i) {
+        const lats = (m.pings || []).filter(p => p.latency_ms != null).map(p => p.latency_ms);
+      %>'<%= m.id %>': [<%- lats.join(',') %>]<% if (i < it.monitors.length - 1) { %>,<% } %>
+      <% }) %>
+    };
+
+    function drawSparkline(values, el) {
+      const W = 120, H = 32;
+      if (!values.length) { el.innerHTML = ''; return; }
+      const max = Math.max(...values, 1);
+      const min = Math.min(...values, 0);
+      const range = max - min || 1;
+      const step = W / Math.max(values.length - 1, 1);
+      const pts = values.map((v, i) => {
+        const x = i * step;
+        const y = H - ((v - min) / range) * (H - 4) - 2;
+        return `${x},${y}`;
+      }).join(' ');
+      const svg = document.createElementNS('http://www.w3.org/2000/svg', 'svg');
+      svg.setAttribute('viewBox', `0 0 ${W} ${H}`);
+      svg.setAttribute('width', W);
+      svg.setAttribute('height', H);
+      const pl = document.createElementNS('http://www.w3.org/2000/svg', 'polyline');
+      pl.setAttribute('points', pts);
+      pl.setAttribute('fill', 'none');
+      pl.setAttribute('stroke', '#60a5fa');
+      pl.setAttribute('stroke-width', '1.5');
+      pl.setAttribute('stroke-linecap', 'round');
+      pl.setAttribute('stroke-linejoin', 'round');
+      svg.appendChild(pl);
+      const old = el.querySelector('svg');
+      if (old) old.replaceWith(svg); else el.appendChild(svg);
+    }
+
+    // SSE: update cards in realtime
     watchAccount((ping) => {
       const card = document.querySelector(`[data-monitor-id="${ping.monitor_id}"]`);
       if (!card) return;
@@ -88,30 +124,13 @@
       if (ping.latency_ms != null) card.querySelector('.stat-latency').textContent = ping.latency_ms + 'ms';
       card.querySelector('.stat-last').innerHTML = timeAgo(ping.checked_at);
 
-      // Sparkline — append point to existing polyline, drop oldest, no refetch
+      // Sparkline — update buffer and redraw locally
       if (ping.latency_ms != null) {
+        const buf = _sparkData[ping.monitor_id] = _sparkData[ping.monitor_id] || [];
+        buf.push(ping.latency_ms);
+        if (buf.length > 20) buf.shift();
         const sparkEl = card.querySelector('.stat-sparkline');
-        const polyline = sparkEl?.querySelector('polyline');
-        if (polyline) {
-          const pts = polyline.getAttribute('points').trim().split(' ').filter(Boolean);
-          const W = 120, H = 32;
-          // Parse existing points
-          let coords = pts.map(p => p.split(',').map(Number));
-          // Extract just y-values (latencies are encoded in y relative to scale)
-          // Easier: maintain a data attr on the svg with the raw values
-          const svg = sparkEl.querySelector('svg');
-          let vals = svg?.dataset.vals ? svg.dataset.vals.split(',').map(Number) : [];
-          vals.push(ping.latency_ms);
-          if (vals.length > 20) vals.shift();
-          if (svg) svg.dataset.vals = vals.join(',');
-          // Redraw polyline in place
-          const max = Math.max(...vals, 1);
-          const min = Math.min(...vals, 0);
-          const range = max - min || 1;
-          const step = W / Math.max(vals.length - 1, 1);
-          const newPts = vals.map((v, i) => `${i * step},${H - ((v - min) / range) * (H - 4) - 2}`).join(' ');
-          polyline.setAttribute('points', newPts);
-        }
+        if (sparkEl) drawSparkline(buf, sparkEl);
       }
     });
   </script>