Gio.OutputStream.prototype.close_async

function close_async(io_priority: Number(gint), cancellable: Gio.Cancellable, callback: Gio.AsyncReadyCallback): void {
    // Gjs wrapper for g_output_stream_close_async()
}
  

Requests an asynchronous close of the stream, releasing resources related to it. When the operation is finished callback will be called. You can then call Gio.OutputStream.prototype.close_finish to get the result of the operation.

For behaviour details see Gio.OutputStream.prototype.close.

The asyncronous methods have a default fallback that uses threads to implement asynchronicity, so they are optional for inheriting classes. However, if you override one you must override all.