diff --git a/index.html b/index.html
index 5dd1532..ce97e5e 100644
--- a/index.html
+++ b/index.html
@@ -87,16 +87,16 @@
 			}
 		]
 		var gantt_chart = new Gantt(".gantt-target", tasks, {
-			on_click: function (task) {
+			on_click: task => {
 				console.log(task);
 			},
-			on_date_change: function(task, start, end) {
+			on_date_change: (task, start, end) => {
 				console.log(task, start, end);
 			},
-			on_progress_change: function(task, progress) {
+			on_progress_change: (task, progress) => {
 				console.log(task, progress);
 			},
-			on_view_change: function(mode) {
+			on_view_change: (mode) => {
 				console.log(mode);
 			},
 			view_mode: 'Month',