alter argument order of throttle.throttle

and beef up its docstring

Author: alexcjohnson

src/components/fx/hover.js

@@ -70,9 +70,9 @@ exports.hover = function hover(gd, evt, subplot, noHoverEvent) {
     gd = Lib.getGraphDiv(gd);
 
     Lib.throttle(
-        function() { _hover(gd, evt, subplot, noHoverEvent); },
+        gd._fullLayout._uid + constants.HOVERID,
         constants.HOVERMINTIME,
-        gd._fullLayout._uid + constants.HOVERID
+        function() { _hover(gd, evt, subplot, noHoverEvent); }
     );
 };
 

src/lib/throttle.js

@@ -18,12 +18,13 @@ var timerCache = {};
  * So the first and last events in a train are always executed (eventually)
  * but some of the events in the middle can be dropped.
  *
- * @param {function} callback: the function to throttle
  * @param {string} id: an identifier to mark events to throttle together
  * @param {number} minInterval: minimum time, in milliseconds, between
  *   invocations of `callback`
+ * @param {function} callback: the function to throttle. `callback` itself
+ *   should be a purely synchronous function.
  */
-exports.throttle = function throttle(callback, minInterval, id) {
+exports.throttle = function throttle(id, minInterval, callback) {
     var cache = timerCache[id];
     var now = Date.now();
 

src/plots/cartesian/select.js

@@ -184,6 +184,8 @@ module.exports = function prepSelect(e, startX, startY, dragOptions, mode) {
         }
 
         throttle.throttle(
+            throttleID,
+            constants.SELECTDELAY,
             function() {
                 selection = [];
                 for(i = 0; i < searchTraces.length; i++) {
@@ -202,9 +204,7 @@ module.exports = function prepSelect(e, startX, startY, dragOptions, mode) {
                 eventData = {points: selection};
                 fillRangeItems(eventData, poly, pts);
                 dragOptions.gd.emit('plotly_selecting', eventData);
-            },
-            constants.SELECTDELAY,
-            throttleID
+            }
         );
     };