[update] onbeforeviewchange article

Refresh event signature and clean view-change details

Author: mlakatkou

docs/api/event/onbeforeviewchange.md

@@ -10,23 +10,23 @@ description: "fires before the user changes the current view to some other one"
 
 @short: Fires before the user changes the current view to some other one
 
-@signature: onBeforeViewChange: (old_mode: string, old_date: object, mode: string, date: object) =\> boolean
+@signature: onBeforeViewChange: (old_mode: string, old_date: Date, mode: string, date: Date) =\> boolean
 
 ### Parameters
 
 - `old_mode` - (required) *string* - the currently active view
-- `old_date` - (required) *object* - the currently active date
+- `old_date` - (required) *Date* - the currently active date
 - `mode` - (required) *string* - the new view
-- `date` - (required) *object* - the new date
+- `date` - (required) *Date* - the new date
 
 ### Returns
-- ` result` - (boolean) - defines whether the default action of the event will be triggered (<b>true</b>) or canceled (<b>false</b>)
+- `result` - (boolean) - defines whether the default action of the event will be triggered (`true`) or canceled (`false`)
 
 ### Example
 
 ~~~jsx
-scheduler.attachEvent("onBeforeViewChange", function(old_mode,old_date,mode,date){
-    //any custom logic here
+scheduler.attachEvent("onBeforeViewChange", (old_mode, old_date, mode, date) => {
+    // any custom logic here
     return true;
 });
 ~~~
@@ -36,5 +36,5 @@ scheduler.attachEvent("onBeforeViewChange", function(old_mode,old_date,mode,date
 
 ### Details
 
-- The event is blockable. Return *false* and the scheduler will leave the current view opened.
-- The event also fires when the scheduler is initially being rendered on the page. In this case, the **old_mode** and **old_date** parameters are underfined.
+- The event is blockable. Return `false`, and the Scheduler will leave the current view open.
+- The event also fires when the Scheduler is initially rendered on the page. In this case, the `old_mode` and `old_date` parameters are undefined.