some linting & commenting in dragbox.js

Author: etpinard

src/plots/cartesian/dragbox.js

@@ -280,16 +280,22 @@ function makeDragBox(gd, plotinfo, x, y, w, h, ns, ew) {
 
     dragElement.init(dragOptions);
 
-    var x0,
-        y0,
-        box,
-        lum,
-        path0,
-        dimmed,
-        zoomMode,
-        zb,
-        corners;
-
+    // x/y px position at start of drag
+    var x0, y0;
+    // bbox object of the zoombox
+    var box;
+    // luminance of bg behind zoombox
+    var lum;
+    // zoombox path outline
+    var path0;
+    // is zoombox dimmed (during drag)
+    var dimmed;
+    // 'x'-only, 'y' or 'xy' zooming
+    var zoomMode;
+    // zoombox d3 selection
+    var zb;
+    // zoombox corner d3 selection
+    var corners;
     // zoom takes over minDrag, so it also has to take over gd._dragged
     var zoomDragged;
 
@@ -305,9 +311,7 @@ function makeDragBox(gd, plotinfo, x, y, w, h, ns, ew) {
         dimmed = false;
         zoomMode = 'xy';
         zoomDragged = false;
-
         zb = makeZoombox(zoomlayer, lum, xs, ys, path0);
-
         corners = makeCorners(zoomlayer, xs, ys);
     }