Use a BBOX loading strategy by default

src/objectliterals.jsdoc

@@ -910,7 +910,7 @@
  * @property {ol.Extent|undefined} extent Extent.
  * @property {ol.format.Feature} format Format.
  * @property {function(this: ol.source.ServerVector, ol.Extent, number, ol.proj.Projection)} loadingFunction Loading function.
- * @property {function(ol.Extent, number): Array.<ol.Extent>} loadingStrategy Loading strategy.
+ * @property {function(ol.Extent, number): Array.<ol.Extent>|undefined} loadingStrategy Loading strategy.  Default is `ol.loadingstrategy.bbox`.
  * @property {string|undefined} logo Logo.
  * @property {ol.proj.ProjectionLike} projection Projection.
  */

src/ol/source/servervectorsource.js

@@ -3,6 +3,7 @@
 goog.provide('ol.source.ServerVector');
 
 goog.require('ol.extent');
+goog.require('ol.loadingstrategy');
 goog.require('ol.source.FormatVector');
 goog.require('ol.structs.RBush');
 
@@ -40,7 +41,8 @@ ol.source.ServerVector = function(options) {
    * @private
    * @type {function(ol.Extent, number): Array.<ol.Extent>}
    */
-  this.loadingStrategy_ = options.loadingStrategy;
+  this.loadingStrategy_ = goog.isDef(options.loadingStrategy) ?
+      options.loadingStrategy : ol.loadingstrategy.bbox;
 
   /**
    * @private