Add zDirection to options

src/ol/source/TileJSON.js

@@ -59,6 +59,9 @@ import {jsonp as requestJSONP} from '../net.js';
  * @property {boolean} [wrapX=true] Whether to wrap the world horizontally.
  * @property {number} [transition] Duration of the opacity transition for rendering.
  * To disable the opacity transition, pass `transition: 0`.
+ * @property {number|import("../array.js").NearestDirectionFunction} [zDirection=0]
+ * Choose whether to use tiles with a higher or lower zoom level when between integer
+ * zoom levels. See {@link module:ol/tilegrid/TileGrid~TileGrid#getZForResolution}.
  */
 
 /**
@@ -82,6 +85,7 @@ class TileJSON extends TileImage {
       tileLoadFunction: options.tileLoadFunction,
       wrapX: options.wrapX !== undefined ? options.wrapX : true,
       transition: options.transition,
+      zDirection: options.zDirection,
     });
 
     /**