Use readonly over getter for exposing events

Fixes #4164

src/common/services/BufferService.ts

@@ -23,9 +23,9 @@ export class BufferService extends Disposable implements IBufferService {
   public isUserScrolling: boolean = false;
 
   private _onResize = new EventEmitter<{ cols: number, rows: number }>();
-  public get onResize(): IEvent<{ cols: number, rows: number }> { return this._onResize.event; }
+  public readonly onResize = this._onResize.event;
   private _onScroll = new EventEmitter<number>();
-  public get onScroll(): IEvent<number> { return this._onScroll.event; }
+  public readonly onScroll = this._onScroll.event;
 
   public get buffer(): IBuffer { return this.buffers.active; }
 

src/common/services/CoreMouseService.ts

@@ -170,9 +170,11 @@ export class CoreMouseService implements ICoreMouseService {
   private _encodings: { [name: string]: CoreMouseEncoding } = {};
   private _activeProtocol: string = '';
   private _activeEncoding: string = '';
-  private _onProtocolChange = new EventEmitter<CoreMouseEventType>();
   private _lastEvent: ICoreMouseEvent | null = null;
 
+  private _onProtocolChange = new EventEmitter<CoreMouseEventType>();
+  public readonly onProtocolChange =  this._onProtocolChange.event;
+
   constructor(
     @IBufferService private readonly _bufferService: IBufferService,
     @ICoreService private readonly _coreService: ICoreService
@@ -225,13 +227,6 @@ export class CoreMouseService implements ICoreMouseService {
     this._lastEvent = null;
   }
 
-  /**
-   * Event to announce changes in mouse tracking.
-   */
-  public get onProtocolChange(): IEvent<CoreMouseEventType> {
-    return this._onProtocolChange.event;
-  }
-
   /**
    * Triggers a mouse event to be sent.
    *

src/common/services/CoreService.ts

@@ -35,11 +35,11 @@ export class CoreService extends Disposable implements ICoreService {
   private _scrollToBottom: (() => void) | undefined;
 
   private _onData = this.register(new EventEmitter<string>());
-  public get onData(): IEvent<string> { return this._onData.event; }
+  public readonly onData = this._onData.event;
   private _onUserInput = this.register(new EventEmitter<void>());
-  public get onUserInput(): IEvent<void> { return this._onUserInput.event; }
+  public readonly onUserInput = this._onUserInput.event;
   private _onBinary = this.register(new EventEmitter<string>());
-  public get onBinary(): IEvent<string> { return this._onBinary.event; }
+  public readonly onBinary = this._onBinary.event;
 
   constructor(
     // TODO: Move this into a service

src/common/services/DecorationService.ts

@@ -28,9 +28,9 @@ export class DecorationService extends Disposable implements IDecorationService
   private readonly _decorations: SortedList<IInternalDecoration> = new SortedList(e => e?.marker.line);
 
   private _onDecorationRegistered = this.register(new EventEmitter<IInternalDecoration>());
-  public get onDecorationRegistered(): IEvent<IInternalDecoration> { return this._onDecorationRegistered.event; }
+  public readonly onDecorationRegistered = this._onDecorationRegistered.event;
   private _onDecorationRemoved = this.register(new EventEmitter<IInternalDecoration>());
-  public get onDecorationRemoved(): IEvent<IInternalDecoration> { return this._onDecorationRemoved.event; }
+  public readonly onDecorationRemoved = this._onDecorationRemoved.event;
 
   public get decorations(): IterableIterator<IInternalDecoration> { return this._decorations.values(); }
 
@@ -99,7 +99,7 @@ class Decoration extends Disposable implements IInternalDecoration {
 
   public readonly onRenderEmitter = this.register(new EventEmitter<HTMLElement>());
   public readonly onRender = this.onRenderEmitter.event;
-  private _onDispose = this.register(new EventEmitter<void>());
+  private readonly _onDispose = this.register(new EventEmitter<void>());
   public readonly onDispose = this._onDispose.event;
 
   private _cachedBg: IColor | undefined | null = null;

src/common/services/OptionsService.ts

@@ -58,7 +58,7 @@ export class OptionsService implements IOptionsService {
   public options: Required<ITerminalOptions>;
 
   private _onOptionChange = new EventEmitter<string>();
-  public get onOptionChange(): IEvent<string> { return this._onOptionChange.event; }
+  public readonly onOptionChange = this._onOptionChange.event;
 
   constructor(options: Partial<ITerminalOptions>) {
     // set the default value of each option

src/common/services/UnicodeService.ts

@@ -13,8 +13,9 @@ export class UnicodeService implements IUnicodeService {
   private _providers: {[key: string]: IUnicodeVersionProvider} = Object.create(null);
   private _active: string = '';
   private _activeProvider: IUnicodeVersionProvider;
+
   private _onChange = new EventEmitter<string>();
-  public get onChange(): IEvent<string> { return this._onChange.event; }
+  public readonly onChange = this._onChange.event;
 
   constructor() {
     const defaultProvider = new UnicodeV6();