Redesign d3_eventSuppress slightly.

d3.js

@@ -409,16 +409,15 @@ d3 = function() {
     while (s = e.sourceEvent) e = s;
     return e;
   }
-  function d3_eventSuppress(name) {
-    var w = d3.select(d3_window);
-    function unbind() {
-      w.on(name + ".suppress", null);
+  function d3_eventSuppress(target, type) {
+    function off() {
+      target.on(type, null);
     }
-    w.on(name + ".suppress", function() {
+    target.on(type, function() {
       d3_eventCancel();
-      unbind();
+      off();
     }, true);
-    setTimeout(unbind, 0);
+    setTimeout(off, 0);
   }
   function d3_eventDispatch(target) {
     var dispatch = new d3_dispatch(), i = 0, n = arguments.length;
@@ -535,7 +534,7 @@ d3 = function() {
         });
         if (moved) {
           d3_eventCancel();
-          if (d3.event.target === eventTarget) d3_eventSuppress("click");
+          if (d3.event.target === eventTarget) d3_eventSuppress(w, "click");
         }
         w.on(touchId != null ? "touchmove.drag-" + touchId : "mousemove.drag", null).on(touchId != null ? "touchend.drag-" + touchId : "mouseup.drag", null);
       }
@@ -1178,7 +1177,7 @@ d3 = function() {
       function mouseup() {
         if (moved) d3_eventCancel();
         w.on("mousemove.zoom", null).on("mouseup.zoom", null);
-        if (moved && d3.event.target === eventTarget) d3_eventSuppress("click");
+        if (moved && d3.event.target === eventTarget) d3_eventSuppress(w, "click.zoom");
       }
     }
     function mousewheel() {

src/behavior/drag.js

@@ -65,7 +65,7 @@ d3.behavior.drag = function() {
       // if moved, prevent the mouseup (and possibly click) from propagating
       if (moved) {
         d3_eventCancel();
-        if (d3.event.target === eventTarget) d3_eventSuppress('click');
+        if (d3.event.target === eventTarget) d3_eventSuppress(w, "click");
       }
 
       w .on(touchId != null ? "touchmove.drag-" + touchId : "mousemove.drag", null)

src/behavior/zoom.js

@@ -116,7 +116,7 @@ d3.behavior.zoom = function() {
     function mouseup() {
       if (moved) d3_eventCancel();
       w.on("mousemove.zoom", null).on("mouseup.zoom", null);
-      if (moved && d3.event.target === eventTarget) d3_eventSuppress('click');
+      if (moved && d3.event.target === eventTarget) d3_eventSuppress(w, "click.zoom");
     }
   }
 

src/event/event.js

@@ -13,20 +13,13 @@ function d3_eventSource() {
   return e;
 }
 
-// In some cases, e.g. on dragend of behavior.zoom and behavior.drag, we need
-// to suppress an event that fires immediately.
-function d3_eventSuppress(name) {
-  var w = d3.select(d3_window);
-  function unbind() {
-    w.on(name + ".suppress", null);
-  }
-  w.on(name + ".suppress", function() {
-    // prevent the subsequent event from propagating (e.g., for anchors)
-    d3_eventCancel();
-    unbind();
-  }, true);
-  // clear the handler after a 0ms timeout in case it doesn't fire after all
-  setTimeout(unbind, 0);
+// Registers an event listener for the specified target that cancels the next
+// event for the specified type, but only if it occurs immediately. This is
+// useful to disambiguate dragging from clicking.
+function d3_eventSuppress(target, type) {
+  function off() { target.on(type, null); }
+  target.on(type, function() { d3_eventCancel(); off(); }, true);
+  setTimeout(off, 0); // clear the handler if it doesn't fire
 }
 
 // Like d3.dispatch, but for custom events abstracting native UI events. These