Merge pull request #549 from jpmorganchase/viewer-table-ownership

Added table ownership flag to `<perspective-viewer>` `delete()` method

packages/perspective-viewer/src/js/viewer.js

@@ -457,11 +457,13 @@ class PerspectiveViewer extends ActionElement {
      * user state).  This (or the underlying `perspective.table`'s equivalent
      * method) must be called in order for its memory to be reclaimed.
      *
+     * @param {boolean} delete_table Should a delete call also be made to the
+     * underlying `table()`.
      * @returns {Promise<boolean>} Whether or not this call resulted in the
      * underlying `perspective.table` actually being deleted.
      */
-    delete() {
-        let x = this._clear_state();
+    delete(delete_table = true) {
+        let x = this._clear_state(delete_table);
         if (this._plugin.delete) {
             this._plugin.delete.call(this);
         }

packages/perspective-viewer/src/js/viewer/perspective_element.js

@@ -312,7 +312,7 @@ export class PerspectiveElement extends StateElement {
         return () => this.setAttribute("render_time", performance.now() - t);
     }
 
-    _clear_state() {
+    _clear_state(clear_table = true) {
         if (this._task) {
             this._task.cancel();
         }
@@ -324,7 +324,7 @@ export class PerspectiveElement extends StateElement {
             view.remove_update(this._view_updater);
             view.remove_delete();
         }
-        if (this._table) {
+        if (this._table && clear_table) {
             const table = this._table;
             this._table = undefined;
             if (table._owner_viewer && table._owner_viewer === this) {