Merge pull request microsoft#352 from saschanaz/callbackinterface

Fix callback interfaces

Author: mhegazy

TS.fsx

@@ -684,7 +684,6 @@ module Emit =
         | "DOMString" -> "string"
         | "DOMTimeStamp" -> "number"
         | "EndOfStreamError" -> "number"
-        | "EventListener" -> "EventListenerOrEventListenerObject"
         | "double" | "float" -> "number"
         | "object" -> "any"
         | "ReadyState" -> "string"
@@ -838,11 +837,14 @@ module Emit =
             (if p.Variadic then "[]" else "")
         String.Join(", ", (List.map paramToString ps))
 
-    let EmitCallBackInterface (i:Browser.Interface) =
-        Pt.Printl "interface %s {" i.Name
-        Pt.PrintWithAddedIndent "(evt: Event): void;"
-        Pt.Printl "}"
-        Pt.Printl ""
+    let EmitCallBackInterface flavor (i:Browser.Interface) =
+        if ShouldKeep flavor i then
+            let m = i.Methods.Value.Methods.[0]
+            let overload = (GetOverloads (Function.Method m) false).[0]
+            let paramsString = ParamsToString overload.ParamCombinations
+            let returnType = DomTypeToTsType m.Type
+            Pt.Printl "type %s = (%s) => %s | { %s(%s): %s; };" i.Name paramsString returnType m.Name.Value paramsString returnType
+            Pt.Printl ""
 
     let EmitCallBackFunctions flavor =
         let emitCallbackFunctionsFromJson (cb: InputJson.InputJsonType.Root) =
@@ -1064,7 +1066,7 @@ module Emit =
 
         let emitStringEventHandler (addOrRemove: string) =
             Pt.Printl
-                "%s%sEventListener(type: string, listener: EventListenerOrEventListenerObject, options?: boolean | %s): void;"
+                "%s%sEventListener(type: string, listener: EventListener, options?: boolean | %s): void;"
                 fPrefix addOrRemove (getOptionsType addOrRemove)
 
         let tryEmitTypedEventHandlerForInterface (addOrRemove: string) =
@@ -1484,15 +1486,12 @@ module Emit =
         Pt.Printl ""
 
         EmitDictionaries flavor
-        browser.CallbackInterfaces.Interfaces |> Array.iter EmitCallBackInterface
+        browser.CallbackInterfaces.Interfaces |> Array.iter (EmitCallBackInterface flavor)
         EmitNonCallbackInterfaces flavor
 
         // Add missed interface definition from the spec
         InputJson.getAddedItems InputJson.Interface flavor |> Array.iter EmitAddedInterface
 
-        Pt.Printl "declare type EventListenerOrEventListenerObject = EventListener | EventListenerObject;"
-        Pt.Printl ""
-
         EmitCallBackFunctions flavor
 
         if flavor <> Worker then