Use ScalaJS Function1 and fix getAsString

Author: zetashift

api-reports/2_12.txt

@@ -1306,11 +1306,11 @@ DataTransfer[JT] def setData(format: String, data: String): Unit
 DataTransfer[JT] def setDragImage(image: Element, x: Double, y: Double): Unit
 DataTransfer[JT] def types: FrozenArray[String]
 DataTransferItem[JC] def getAsFile(): File
-DataTransferItem[JC] def getAsString(callback: Function1[String, Unit]): Unit
+DataTransferItem[JC] def getAsString(callback: js.Function1[String, Unit]): Unit
 DataTransferItem[JC] def kind: DragDataItemKind
 DataTransferItem[JC] def `type`: String
-DataTransferItemList[JC] def add(data: File): Unit
-DataTransferItemList[JC] def add(data: String, `type`: String): Unit
+DataTransferItemList[JC] def add(data: File): DataTransferItem
+DataTransferItemList[JC] def add(data: String, `type`: String): DataTransferItem
 DataTransferItemList[JC] @js.annotation.JSBracketAccess def apply(index: Int): DataTransferItem
 DataTransferItemList[JC] def clear(): Unit
 DataTransferItemList[JC] def length: Int

api-reports/2_13.txt

@@ -1306,11 +1306,11 @@ DataTransfer[JT] def setData(format: String, data: String): Unit
 DataTransfer[JT] def setDragImage(image: Element, x: Double, y: Double): Unit
 DataTransfer[JT] def types: FrozenArray[String]
 DataTransferItem[JC] def getAsFile(): File
-DataTransferItem[JC] def getAsString(callback: Function1[String, Unit]): Unit
+DataTransferItem[JC] def getAsString(callback: js.Function1[String, Unit]): Unit
 DataTransferItem[JC] def kind: DragDataItemKind
 DataTransferItem[JC] def `type`: String
-DataTransferItemList[JC] def add(data: File): Unit
-DataTransferItemList[JC] def add(data: String, `type`: String): Unit
+DataTransferItemList[JC] def add(data: File): DataTransferItem
+DataTransferItemList[JC] def add(data: String, `type`: String): DataTransferItem
 DataTransferItemList[JC] @js.annotation.JSBracketAccess def apply(index: Int): DataTransferItem
 DataTransferItemList[JC] def clear(): Unit
 DataTransferItemList[JC] def length: Int

dom/src/main/scala/org/scalajs/dom/DataTransferItem.scala

@@ -21,7 +21,7 @@ class DataTransferItem private[this] extends js.Object {
   def `type`: String = js.native
 
   /** Invokes the callback with the string data as the argument, if the drag data item kind is text. */
-  def getAsString(callback: Function1[String, Unit]): Unit = js.native
+  def getAsString(callback: js.Function1[String, Unit]): Unit = js.native
 
   /** Returns a File object, if the drag data item kind is File. */
   def getAsFile(): File = js.native

dom/src/main/scala/org/scalajs/dom/DataTransferItemList.scala

@@ -22,12 +22,12 @@ class DataTransferItemList private[this] extends js.Object {
   /** Adds a new entry for the given data to the drag data store. If the data is plain text then a type string has to be
     * provided also.
     */
-  def add(data: String, `type`: String): Unit = js.native
+  def add(data: String, `type`: String): DataTransferItem = js.native
 
   /** Adds a new entry for the given data to the drag data store. If the data is plain text then a type string has to be
     * provided also.
     */
-  def add(data: File): Unit = js.native
+  def add(data: File): DataTransferItem = js.native
 
   /** Removes the indexth entry in the drag data store. */
   def remove(index: Int): Unit = js.native