diff --git a/src/becca/becca_loader.js b/src/becca/becca_loader.js
index ad64570a0..ecf7a7441 100644
--- a/src/becca/becca_loader.js
+++ b/src/becca/becca_loader.js
@@ -1,7 +1,7 @@
 "use strict";
 
 const sql = require('../services/sql');
-const eventService = require('../services/events.js');
+const eventService = require('../services/events');
 const becca = require('./becca.js');
 const sqlInit = require('../services/sql_init.js');
 const log = require('../services/log');
diff --git a/src/routes/api/branches.js b/src/routes/api/branches.js
index 4149a7315..55576665e 100644
--- a/src/routes/api/branches.js
+++ b/src/routes/api/branches.js
@@ -10,7 +10,7 @@ const TaskContext = require('../../services/task_context.js');
 const branchService = require('../../services/branches.js');
 const log = require('../../services/log');
 const ValidationError = require('../../errors/validation_error');
-const eventService = require("../../services/events.js");
+const eventService = require("../../services/events");
 
 /**
  * Code in this file deals with moving and cloning branches. The relationship between note and parent note is unique
diff --git a/src/routes/api/login.js b/src/routes/api/login.js
index ec5891c28..6d57519d4 100644
--- a/src/routes/api/login.js
+++ b/src/routes/api/login.js
@@ -7,7 +7,7 @@ const instanceId = require('../../services/instance_id.js');
 const passwordEncryptionService = require('../../services/encryption/password_encryption.js');
 const protectedSessionService = require('../../services/protected_session');
 const appInfo = require('../../services/app_info.js');
-const eventService = require('../../services/events.js');
+const eventService = require('../../services/events');
 const sqlInit = require('../../services/sql_init.js');
 const sql = require('../../services/sql');
 const ws = require('../../services/ws.js');
diff --git a/src/services/entity_changes.js b/src/services/entity_changes.js
index 209afc359..a2b9c99ca 100644
--- a/src/services/entity_changes.js
+++ b/src/services/entity_changes.js
@@ -53,7 +53,7 @@ function putNoteReorderingEntityChange(parentNoteId, componentId) {
         instanceId
     });
 
-    const eventService = require('./events.js');
+    const eventService = require('./events');
 
     eventService.emit(eventService.ENTITY_CHANGED, {
         entityName: 'note_reordering',
diff --git a/src/services/events.js b/src/services/events.ts
similarity index 84%
rename from src/services/events.js
rename to src/services/events.ts
index 51c30be17..fffcc3982 100644
--- a/src/services/events.js
+++ b/src/services/events.ts
@@ -11,13 +11,16 @@ const ENTITY_DELETE_SYNCED = "ENTITY_DELETE_SYNCED";
 const CHILD_NOTE_CREATED = "CHILD_NOTE_CREATED";
 const NOTE_CONTENT_CHANGE = "NOTE_CONTENT_CHANGED";
 
-const eventListeners = {};
+type EventType = string | string[];
+type EventListener = (data: any) => void;
+
+const eventListeners: Record<string, EventListener[]> = {};
 
 /**
  * @param {string|string[]}eventTypes - can be either single event or an array of events
  * @param listener
  */
-function subscribe(eventTypes, listener) {
+function subscribe(eventTypes: EventType, listener: EventListener) {
     if (!Array.isArray(eventTypes)) {
         eventTypes = [ eventTypes ];
     }
@@ -28,7 +31,7 @@ function subscribe(eventTypes, listener) {
     }
 }
 
-function subscribeBeccaLoader(eventTypes, listener) {
+function subscribeBeccaLoader(eventTypes: EventType, listener: EventListener) {
     if (!Array.isArray(eventTypes)) {
         eventTypes = [ eventTypes ];
     }
@@ -41,7 +44,7 @@ function subscribeBeccaLoader(eventTypes, listener) {
     }
 }
 
-function emit(eventType, data) {
+function emit(eventType: string, data: any) {
     const listeners = eventListeners[eventType];
 
     if (listeners) {
@@ -49,7 +52,7 @@ function emit(eventType, data) {
             try {
                 listener(data);
             }
-            catch (e) {
+            catch (e: any) {
                 log.error(`Listener threw error: ${e.message}, stack: ${e.stack}`);
                 // we won't stop execution because of listener
             }
@@ -57,7 +60,7 @@ function emit(eventType, data) {
     }
 }
 
-module.exports = {
+export = {
     subscribe,
     subscribeBeccaLoader,
     emit,
diff --git a/src/services/handlers.js b/src/services/handlers.js
index 769c69485..d5a55fafe 100644
--- a/src/services/handlers.js
+++ b/src/services/handlers.js
@@ -1,4 +1,4 @@
-const eventService = require('./events.js');
+const eventService = require('./events');
 const scriptService = require('./script.js');
 const treeService = require('./tree.js');
 const noteService = require('./notes.js');
diff --git a/src/services/notes.js b/src/services/notes.js
index 050729c4c..214975a95 100644
--- a/src/services/notes.js
+++ b/src/services/notes.js
@@ -2,7 +2,7 @@ const sql = require('./sql');
 const optionService = require('./options.js');
 const dateUtils = require('./date_utils');
 const entityChangesService = require('./entity_changes.js');
-const eventService = require('./events.js');
+const eventService = require('./events');
 const cls = require('../services/cls');
 const protectedSessionService = require('../services/protected_session');
 const log = require('../services/log');
diff --git a/src/services/sync_update.js b/src/services/sync_update.js
index 5db427e1f..6581066f4 100644
--- a/src/services/sync_update.js
+++ b/src/services/sync_update.js
@@ -1,7 +1,7 @@
 const sql = require('./sql');
 const log = require('./log');
 const entityChangesService = require('./entity_changes.js');
-const eventService = require('./events.js');
+const eventService = require('./events');
 const entityConstructor = require('../becca/entity_constructor.js');
 const ws = require('./ws.js');
 
diff --git a/src/share/shaca/shaca_loader.js b/src/share/shaca/shaca_loader.js
index aef4f36d5..5d1648f49 100644
--- a/src/share/shaca/shaca_loader.js
+++ b/src/share/shaca/shaca_loader.js
@@ -8,7 +8,7 @@ const SBranch = require('./entities/sbranch.js');
 const SAttribute = require('./entities/sattribute.js');
 const SAttachment = require('./entities/sattachment.js');
 const shareRoot = require('../share_root.js');
-const eventService = require('../../services/events.js');
+const eventService = require('../../services/events');
 
 function load() {
     const start = Date.now();