Added writeAsync(...) methods to provide promise support

Author: ldaniels528

src/main/scala/io/scalajs/nodejs/fs/Fs.scala

@@ -1069,9 +1069,9 @@ trait Fs extends IEventEmitter {
     **/
   def write(fd: FileDescriptor,
             buffer: Buffer | Uint8Array,
-            offset: Int = js.native,
-            length: Int = js.native,
-            position: Int = js.native,
+            offset: Integer = js.native,
+            length: Integer = js.native,
+            position: Integer = js.native,
             callback: FsCallback2[Int, Buffer]): Unit = js.native
 
   /**

src/main/scala/io/scalajs/nodejs/fs/package.scala

@@ -5,6 +5,7 @@ import io.scalajs.util.PromiseHelper._
 
 import scala.concurrent.Promise
 import scala.scalajs.js
+import scala.scalajs.js.typedarray.Uint8Array
 import scala.scalajs.js.|
 
 /**
@@ -124,6 +125,27 @@ package object fs {
     def watchAsync(filename: String, options: FSWatcherOptions = null): Promise[(String, String)] =
       promiseCallback2[String, String](fs.watch(filename, options, _))
 
+    @inline
+    def writeAsync(fd: FileDescriptor,
+                   buffer: Buffer | Uint8Array,
+                   offset: Integer = null,
+                   length: Integer = null,
+                   position: Integer = null): Promise[(FileType, Buffer)] = {
+      promiseWithError2[FileIOError, Int, Buffer](fs.write(fd, buffer, offset, length, position, _))
+    }
+
+    @inline
+    def writeAsync(fd: FileDescriptor, string: String, position: Int, encoding: String): Promise[(FileType, String)] =
+      promiseWithError2[FileIOError, Int, String](fs.write(fd, string, position, encoding, _))
+
+    @inline
+    def writeAsync(fd: FileDescriptor, string: String, position: Int): Promise[(FileType, String)] =
+      promiseWithError2[FileIOError, Int, String](fs.write(fd, string, position, null, _))
+
+    @inline
+    def writeAsync(fd: FileDescriptor, string: String): Promise[(FileType, String)] =
+      promiseWithError2[FileIOError, Int, String](fs.write(fd, string, _))
+
     @inline
     def writeFileAsync(file: String, data: Buffer | String, options: FileOutputOptions = null): Promise[Unit] =
       promiseWithError0[FileIOError](fs.writeFile(file, data, options, _))