diff --git a/api/js/etemplate/et2_widget_countdown.js b/api/js/etemplate/et2_widget_countdown.js
index 6ca4ce28e7..8bd36daa22 100644
--- a/api/js/etemplate/et2_widget_countdown.js
+++ b/api/js/etemplate/et2_widget_countdown.js
@@ -86,11 +86,18 @@ var et2_countdown = /** @class */ (function (_super) {
         var distance = this.time.getTime() - now.getTime();
         if (distance < 0)
             return 0;
-        var alarms = Array.isArray(this.options.alarm) ? this.options.alarm : [this.options.alarm];
-        for (var i = 0; i <= alarms.length; i++) {
-            if (alarms[i] > 0 && alarms[i] == Math.floor(distance / 1000) && typeof this.onAlarm == 'function') {
-                this.onAlarm();
-            }
+        var alarms = [];
+        if (Array.isArray(this.options.alarm)) {
+            alarms = this.options.alarm;
+        }
+        else {
+            alarms[this.options.alarm] = this.options.alarm;
+        }
+        // alarm values should be set as array index to reduce its time complexity from O(n) to O(1)
+        // otherwise the execution time might be more than a second which would cause timer being delayed
+        if (alarms[Math.floor(distance / 1000)] && typeof this.onAlarm == 'function') {
+            console.log('alarm is called');
+            this.onAlarm();
         }
         var values = {
             days: Math.floor(distance / (1000 * 60 * 60 * 24)),
diff --git a/api/js/etemplate/et2_widget_countdown.ts b/api/js/etemplate/et2_widget_countdown.ts
index e795a67921..8c2652688f 100644
--- a/api/js/etemplate/et2_widget_countdown.ts
+++ b/api/js/etemplate/et2_widget_countdown.ts
@@ -121,14 +121,22 @@ export class et2_countdown extends et2_valueWidget {
 
 		if (distance < 0) return 0;
 
-		let alarms = Array.isArray(this.options.alarm) ? this.options.alarm : [this.options.alarm];
-
-		for (let i=0;i<=alarms.length;i++)
+		let alarms = [];
+		if (Array.isArray(this.options.alarm))
 		{
-			if (alarms[i] > 0 && alarms[i] == Math.floor(distance/1000) && typeof this.onAlarm == 'function')
-			{
-				this.onAlarm();
-			}
+			alarms = this.options.alarm;
+		}
+		else
+		{
+			alarms[this.options.alarm] = this.options.alarm;
+		}
+
+		// alarm values should be set as array index to reduce its time complexity from O(n) to O(1)
+		// otherwise the execution time might be more than a second which would cause timer being delayed
+		if (alarms[Math.floor(distance/1000)] && typeof this.onAlarm == 'function')
+		{
+			console.log('alarm is called')
+			this.onAlarm();
 		}
 
 		let values = {