Gio.File.prototype.load_contents_finish

function load_contents_finish(res: Gio.AsyncResult): [ok: Boolean, contents: ByteArray, etag_out: String] {
    // Gjs wrapper for g_file_load_contents_finish()
}

Finishes an asynchronous load of the file's contents. The contents are placed in contents, and length is set to the size of the contents string. The @content should be freed with GLib.free when no longer needed. If etag_out is present, it will be set to the new entity tag for the file.

res: a Gio.AsyncResult
ok: true if the load was successful. If false and @error is present, it will be set appropriately.
contents: a location to place the contents of the file
etag_out: a location to place the current entity tag for the file, or null if the entity tag is not needed