refactor: start files migration nightmare

modules/zoom.js

@@ -0,0 +1,52 @@
+"use strict";
+
+// temporary expose to global
+let scale = 1;
+let viewX = 0;
+let viewY = 0;
+
+window.Zoom = (function () {
+  function onZoom() {
+    const {k, x, y} = d3.event.transform;
+
+    const isScaleChanged = Boolean(scale - k);
+    const isPositionChanged = Boolean(viewX - x || viewY - y);
+    if (!isScaleChanged && !isPositionChanged) return;
+
+    scale = k;
+    viewX = x;
+    viewY = y;
+
+    handleZoom(isScaleChanged, isPositionChanged);
+  }
+  const onZoomDebouced = debounce(onZoom, 50);
+  const zoom = d3.zoom().scaleExtent([1, 20]).on("zoom", onZoomDebouced);
+
+  // zoom to a specific point
+  function to(x, y, z = 8, d = 2000) {
+    const transform = d3.zoomIdentity.translate(x * -z + graphWidth / 2, y * -z + graphHeight / 2).scale(z);
+    svg.transition().duration(d).call(zoom.transform, transform);
+  }
+
+  // reset zoom to initial
+  function reset(d = 1000) {
+    svg.transition().duration(d).call(zoom.transform, d3.zoomIdentity);
+  }
+
+  function scaleExtent([min, max]) {
+    zoom.scaleExtent([min, max]);
+  }
+
+  function translateExtent([x1, y1, x2, y2]) {
+    zoom.translateExtent([
+      [x1, y1],
+      [x2, y2]
+    ]);
+  }
+
+  function scaleTo(element, scale) {
+    zoom.scaleTo(element, scale);
+  }
+
+  return {to, reset, scaleExtent, translateExtent, scaleTo};
+})();