1 files changed, 28 insertions, 0 deletions
diff --git a/actionview/app/assets/javascripts/rails-ujs/utils/event.coffee b/actionview/app/assets/javascripts/rails-ujs/utils/event.coffee
index 8d3ff007ea..a7eee52060 100644
--- a/actionview/app/assets/javascripts/rails-ujs/utils/event.coffee
+++ b/actionview/app/assets/javascripts/rails-ujs/utils/event.coffee
@@ -11,9 +11,26 @@ if typeof CustomEvent isnt 'function'
     evt = document.createEvent('CustomEvent')
     evt.initCustomEvent(event, params.bubbles, params.cancelable, params.detail)
     evt
+
   CustomEvent.prototype = window.Event.prototype
 
+  # Fix setting `defaultPrevented` when `preventDefault()` is called
+  # http://stackoverflow.com/questions/23349191/event-preventdefault-is-not-working-in-ie-11-for-custom-events
+  { preventDefault } = CustomEvent.prototype
+  CustomEvent.prototype.preventDefault = ->
+    result = preventDefault.call(this)
+    if @cancelable and not @defaultPrevented
+      Object.defineProperty(this, 'defaultPrevented', get: -> true)
+    result
+
 # Triggers a custom event on an element and returns false if the event result is false
+# obj::
+#   a native DOM element
+# name::
+#   string that corrspends to the event you want to trigger
+#   e.g. 'click', 'submit'
+# data::
+#   data you want to pass when you dispatch an event
 fire = Rails.fire = (obj, name, data) ->
   event = new CustomEvent(
     name,
@@ -31,6 +48,17 @@ Rails.stopEverything = (e) ->
   e.stopPropagation()
   e.stopImmediatePropagation()
 
+# Delegates events
+# to a specified parent `element`, which fires event `handler`
+# for the specified `selector` when an event of `eventType` is triggered
+# element::
+#   parent element that will listen for events e.g. document
+# selector::
+#   css selector; or an object that has `selector` and `exclude` properties (see: Rails.matches)
+# eventType::
+#   string representing the event e.g. 'submit', 'click'
+# handler::
+#   the event handler to be called
 Rails.delegate = (element, selector, eventType, handler) ->
   element.addEventListener eventType, (e) ->
     target = e.target