diff --git a/bricks/camera.js b/bricks/camera.js
index 38d94cf..efcd0d1 100644
--- a/bricks/camera.js
+++ b/bricks/camera.js
@@ -86,7 +86,7 @@ bricks.Camera = class extends bricks.Popup {
 		this.video.srcObject = this.stream;
 		this.video.play();
 		this.show_cnt = 1;
-		this.task = schedule_once(this.show_picture.bind(this), this.task_period);
+		this.task = schedule_interval(this.show_picture.bind(this), this.task_period);
     }
 	show_picture(){
 		if (this.task_period == 0){
@@ -99,7 +99,6 @@ bricks.Camera = class extends bricks.Popup {
         context.drawImage(this.video, 0, 0);
 		this.dataurl = canvas.toDataURL('image/jpeg', 0.95);
 		this.imgw.set_url(this.dataurl);
-		this.task = schedule_once(this.show_picture.bind(this), this.task_period);
 		this.show_cnt += 1;
 	}
 	switch_recording(){
@@ -141,7 +140,7 @@ bricks.Camera = class extends bricks.Popup {
 	take_picture(event){
 		event.stopPropagation();
 		if (this.task){
-			task.cancel();
+			clearInterval(this.task);
 			this.task = null;
 		}
 		this.task_period = 0;
diff --git a/bricks/countdown.js b/bricks/countdown.js
index 35c9ff9..5c321ab 100644
--- a/bricks/countdown.js
+++ b/bricks/countdown.js
@@ -17,13 +17,13 @@ bricks.TimePassed = class extends bricks.VBox {
 		this.seconds = 0;
 		var t = bricks.formatTime(this.seconds);
 		this.text_w = new bricks.Text({
-			text:this.t, 
+			text:t, 
 			rate:this.text_rate
 		});
 		this.add_widget(this.text_w);
 	}
 	start(){
-		this.task = schedule_once(this.add_one_second.bind(this), 1);
+		this.task = schedule_interval(this.add_one_second.bind(this), 1);
 	}
 		
 	add_one_second(){
@@ -33,7 +33,7 @@ bricks.TimePassed = class extends bricks.VBox {
 		this.task = schedule_once(this.add_one_second.bind(this), 1);
 	}
 	stop(){
-		this.task.cancel();
+		clearInterval(this.task);
 		this.task = null;
 	}
 }
@@ -84,18 +84,23 @@ bricks.Countdown = class extends bricks.VBox {
 		this.add_widget(this.text_w);
 	}
 	start(){
-		schedule_once(this.time_down_second.bind(this), 1)
+		this.task = schedule_interval(this.time_down_second.bind(this), 1)
+	}
+	stop(){
+		if (this.task){
+			clearInterval(this.task);
+		}
+		this.task = null;
 	}
 	time_down_second(){
-		if (this.seconds < 1){
-			this.dispatch('timeout');
-			return;
-		}
 		var h, m, s;
 		this.seconds -= 1;
 		var ts = bricks.formatTime(this.seconds);
 		this.text_w.set_text(ts);
-		schedule_once(this.time_down_second.bind(this), 1)
+		if (this.seconds < 1){
+			stop();
+			this.dispatch('timeout');
+		}
 	}
 }
 
diff --git a/bricks/modal.js b/bricks/modal.js
index f8db462..fecdb5f 100644
--- a/bricks/modal.js
+++ b/bricks/modal.js
@@ -84,7 +84,7 @@ bricks.BaseModal = class extends bricks.Layout {
 		if (this.parent){
 			this.set_css('display', 'none');
 			if (this.timeout_task){
-				this.timeout_task.cancel();
+				clearTimeout(this.timeout_task);
 				this.timeout_task = null;
 			}
 			try {
diff --git a/bricks/recorder.js b/bricks/recorder.js
index f3aa33b..629e4d6 100644
--- a/bricks/recorder.js
+++ b/bricks/recorder.js
@@ -32,10 +32,9 @@ bricks.MediaRecorder = class extends bricks.Popup {
 		this.record_status = 'standby';
 		this.toggle_record.bind('click', this.switch_record.bind(this));
 		this.toggle_record.disabled(true);
-		schedule_once(this.open_recorder.bind(this), 0.1);
+		this.task = schedule_interval(this.open_recorder.bind(this), 0.1);
 	}
 	tick_task(){
-		this.task = schedule_once(this.tick_task.bind(this), this.task_period);
 		this.timepass.set_text(bricks.timeDiff(this.start_time));
 	}
 	async switch_record(){
@@ -96,7 +95,7 @@ bricks.MediaRecorder = class extends bricks.Popup {
 		};
 
 		this.start_time = Date.now();
-		this.task = schedule_once(this.tick_task.bind(this), this.task_period);
+		this.task = schedule_interval(this.tick_task.bind(this), this.task_period);
 		this.mediaRecorder.start();
 		this.dispatch('record_started')
 		console.log("Recording started...");
@@ -116,7 +115,7 @@ bricks.MediaRecorder = class extends bricks.Popup {
 
 	close_recorder(){
 		if (this.task){
-			this.task.cancel();
+			clearInterval(this.task);
 			this.task = null;
 		}
 		if (this.stream){
@@ -242,7 +241,7 @@ bricks.SysVideoRecorder = class extends bricks.MediaRecorder {
 		this.imgw = new bricks.Image({width: '100%'});
 		this.preview.add_widget(this.imgw);
 		this.toggle_record.disabled(false);
-		this.pic_task = schedule_once(this.show_picture.bind(this), this.task_period);
+		this.pic_task = schedule_interval(this.show_picture.bind(this), this.task_period);
 	}
 	async show_picture(){
 		if (this.task_period == 0){
@@ -254,13 +253,11 @@ bricks.SysVideoRecorder = class extends bricks.MediaRecorder {
                         'image.jpg',
                         { type: 'image/jpeg' });
 		this.imgw.set_url(this.dataurl);
-		this.pic_task = schedule_once(this.show_picture.bind(this), 
-									this.task_period);
 	}
 	close_recorder(){
 		super.close_recorder();
 		if (this.pic_task){
-			this.pic_task.cancel();
+			clearInterval(this.pic_task);
 			this.pic_task = null;
 		}
 	}
@@ -270,7 +267,7 @@ bricks.SysCamera= class extends bricks.SysVideoRecorder {
 		console.log('shot it ............');
 		event.stopPropagation();
 		if (this.task){
-			task.cancel();
+			clearInterval(this.task);
 			this.task = null;
 		}
 		this.task_period = 0;
diff --git a/bricks/rtc.js b/bricks/rtc.js
index 4e4a268..5d0a135 100644
--- a/bricks/rtc.js
+++ b/bricks/rtc.js
@@ -140,7 +140,6 @@ bricks.Signaling = class {
 		this.send_data(d);
 		if (this.heartbeat_period > 0){
 			console.log('call login again in', this.heartbeat_period, ' seconds');
-			this.hb_task = schedule_once(this.login.bind(this), this.heartbeat_period);
 		}
 	}
 
diff --git a/bricks/running.js b/bricks/running.js
index 716b8f6..8bf56fc 100644
--- a/bricks/running.js
+++ b/bricks/running.js
@@ -23,18 +23,17 @@ bricks.BaseRunning = class extends bricks.FHBox {
 		this.time_start = new Date().getTime();
 		this.add_widget(this.icon_w);
 		this.add_widget(this.time_w);
-		this.showtime_task = schedule_once(this.show_timepass.bind(this), 0.05);
+		this.showtime_task = schedule_interval(this.show_timepass.bind(this), 0.05);
 	}
 	
 	show_timepass(){
 		var t = new Date().getTime() - this.time_start;
 		var txt = bricks.formatMs(t, 1);
 		this.time_w.set_text(txt);
-		this.showtime_task = schedule_once(this.show_timepass.bind(this), 0.05);
 	}
 	stop_timepass(){
 		if (this.showtime_task){
-			this.showtime_task.cancel();
+			clearInterval(this.showtime_task);
 			this.showtime_task = null;
 		}
 	}
diff --git a/bricks/svg.js b/bricks/svg.js
index 99999cf..227acff 100644
--- a/bricks/svg.js
+++ b/bricks/svg.js
@@ -57,18 +57,17 @@ bricks.Svg = class extends bricks.VBox {
 				this.dom_element.innerHTML = this.svg_text;
 			else
 				this.dom_element.innerHTML = ''
-			this.blink_task = schedule_once(this._blink.bind(this), 
-				this.blinktime);
 		}
 	}
 	start_blink(){
 		if (!this.blink_task){
-			this._blink();
+			this.blink_task = schedule_interval(this._blink.bind(this), 
+				this.blinktime);
 		}
 	}
 	end_blink(){
 		if (this.blink_task)
-			this.blink_task.cancel();
+			clearInterval(this.blink_task);
 		this.blink_task = null;
 	}
 }
diff --git a/bricks/utils.js b/bricks/utils.js
index 6b47fb7..0151076 100644
--- a/bricks/utils.js
+++ b/bricks/utils.js
@@ -358,12 +358,8 @@ var schedule_once = function(f, t){
 }
 
 var schedule_interval = function(f, t){
-	var mf = function(func, t){
-		console.log('arguments:', func, t);
-		func();
-		schedule_once(mf.bind(func, t), t);
-	}
-	schedule_once(mf.bind(f,t), t);
+	t = t * 1000
+	return window.setInterval(f, t);
 }
 
 var debug = function(){
diff --git a/bricks/widget.js b/bricks/widget.js
index c3bd319..31609c8 100644
--- a/bricks/widget.js
+++ b/bricks/widget.js
@@ -550,10 +550,10 @@ bricks.Tooltip = class extends bricks.Text {
 	}
 	hide(){
 		try {
-		if (this.auto_task){
-			this.auto_task.cancel();
-			this.auto_task = null;
-		}
+			if (this.auto_task){
+				clearTimeout(this.auto_task);
+				this.auto_task = null;
+			}
 		} catch(e){
 			console.log('Exception:', e);
 		}
diff --git a/bricks/wterm.js b/bricks/wterm.js
index c68b52b..fa52a52 100644
--- a/bricks/wterm.js
+++ b/bricks/wterm.js
@@ -45,10 +45,6 @@ bricks.Wterm = class extends bricks.JsWidget {
 	destroy(){
 		console.debug('------domoff event, destory this widget');
 		try {
-			if (this.heartbeat_task){
-				this.heartbeat_task.cancel();
-				this.heartbeat_task = null;
-			}
 			this.unbind('element_resize', this.term_resize.bind(this))
 		} catch(e) {
 			console.log('error ', e);
@@ -83,16 +79,6 @@ bricks.Wterm = class extends bricks.JsWidget {
 	send_data(d){
 		this.socket.send(JSON.stringify({type: "input", "data":d}));
 	}
-	send_heartbeat(){
-		this.socket.send(JSON.stringify({ type: "heartbeat"  }));
-	
-	}
-	heartbeat(){
-		if (this.socket.readyState != 1) return;
-		this.send_heartbeat();
-		this.heartbeat_task = schedule_once(this.heartbeat.bind(this), 
-								this.ping_timeout);
-	}
 	async open(){
 		var term_options = bricks.extend({width: "100%", height: "100%"}, this.term_options);
 		var term = new Terminal(term_options);
@@ -120,16 +106,10 @@ bricks.Wterm = class extends bricks.JsWidget {
 		};
 		ws.onclose = (event) => {
 			console.log('websocket closed:', event.code, '--', event.reason);
-			if (this.heartbeat_task) {
-				this.heartbeat_task.cancel();
-				this.heartbeat_task = null;
-			}
 		};
 		ws.onopen = () => {
 			this.send_term_size();
 			this.bind('element_resize', this.term_resize.bind(this))
-			this.heartbeat_task = schedule_once(this.heartbeat.bind(this), 
-							this.ping_timeout);
 		};
 		term.onData((key) => {
 			console.log('key=', key);