wire uPlot tooltips into the existing tooltip system

assets/js/tooltip.js

@@ -0,0 +1,32 @@
+export function uPlotTooltipPlugin (onHover) {
+  let element
+
+  return {
+    hooks: {
+      init: u => {
+        element = u.root.querySelector('.over')
+
+        element.onmouseenter = () => onHover()
+        element.onmouseleave = () => onHover()
+      },
+      setCursor: u => {
+        const { left, top, idx } = u.cursor
+
+        if (idx === null) {
+          onHover()
+        } else {
+          const bounds = element.getBoundingClientRect()
+
+          onHover({
+            left: bounds.left + left + window.pageXOffset,
+            top: bounds.top + top + window.pageYOffset
+          }, {
+            idx,
+            x: u.data[0][idx],
+            y: u.data[1][idx]
+          })
+        }
+      }
+    }
+  }
+}