Merge pull request airbnb#73 from airbnb/event-payloads

[events] add events section, pass a hash not a raw value

Author: hshoff

README.md

@@ -23,6 +23,7 @@
   1. [Naming Conventions](#naming-conventions)
   1. [Accessors](#accessors)
   1. [Constructors](#constructors)
+  1. [Events](#events)
   1. [Modules](#modules)
   1. [jQuery](#jquery)
   1. [ES5 Compatibility](#es5)
@@ -1188,6 +1189,37 @@
     **[[⬆]](#TOC)**
 
 
+## <a name='events'>Events</a>
+
+  - When attaching data payloads to events (whether DOM events or something more proprietary like Backbone events), pass a hash instead of a raw value. This allows a subsequent contributor to add more data to the event payload without finding and updating every handler for the event. For example, instead of:
+    
+    ```js
+    // bad
+    $(this).trigger('listingUpdated', listing.id);
+
+    ...
+
+    $(this).on('listingUpdated', function(e, listingId) {
+      // do something with listingId
+    });
+    ```
+
+    prefer:
+    
+    ```js
+    // good
+    $(this).trigger('listingUpdated', { listingId : listing.id });
+
+    ...
+
+    $(this).on('listingUpdated', function(e, data) {
+      // do something with data.listingId
+    });
+    ```
+
+  **[[⬆]](#TOC)**
+
+
 ## <a name='modules'>Modules</a>
 
   - The module should start with a `!`. This ensures that if a malformed module forgets to include a final semicolon there aren't errors in production when the scripts get concatenated.