add destroy method to remove listener

Author: chrisweb

src/library/core.ts

@@ -126,13 +126,13 @@ export class Waveform {
 
     protected _addClickWaveListener(): void {
 
-        this._canvasElement.addEventListener('click', (event: MouseEvent) => { this._canvasElementClick(event) });
+        this._canvasElement.addEventListener('click', this._canvasElementClick);
 
     }
 
     protected _removeClickWaveListener(): void {
 
-        this._canvasElement.removeEventListener('click', (event: MouseEvent) => { this._canvasElementClick(event) });
+        this._canvasElement.removeEventListener('click', this._canvasElementClick);
 
     }
 
@@ -253,4 +253,10 @@ export class Waveform {
 
         }
     }
+
+    public destroy(): void {
+
+        this._removeClickWaveListener();
+
+    }
 }