Merge pull request #1492 from tradingview/fix-plugin-base-data-update…

…-subscriber

plugin examples: fix plugin base _fireDataUpdated #1491

plugin-examples/src/plugins/plugin-base.ts

@@ -28,6 +28,7 @@ export abstract class PluginBase implements ISeriesPrimitive<Time> {
 	}
 
 	public detached() {
+		this._series?.unsubscribeDataChanged(this._fireDataUpdated);
 		this._chart = undefined;
 		this._series = undefined;
 		this._requestUpdate = undefined;
@@ -41,7 +42,10 @@ export abstract class PluginBase implements ISeriesPrimitive<Time> {
 		return ensureDefined(this._series);
 	}
 
-	private _fireDataUpdated(scope: DataChangedScope) {
+	// This method is a class property to maintain the
+	// lexical 'this' scope (due to the use of the arrow function)
+	// and to ensure its reference stays the same, so we can unsubscribe later.
+	private _fireDataUpdated = (scope: DataChangedScope) => {
 		if (this.dataUpdated) {
 			this.dataUpdated(scope);
 		}