Change the image based on the time

<script language="JavaScript" type="text/javascript">  
 var now = new Date();  
 var hour = now.getHours();  
  
 if (hour <=11){  
    var TimeofDay = "<img src="images/Pic1.jpg">"  
 }else if(hour > 11 && hour <= 17){  
    var TimeofDay = "<img src="images/Pic2.jpg">"  
 }else if(hour > 17){  
    var TimeofDay = "<img src="images/Pic3.jpg">"  
 }  
</script>  
  
<script>  
    document.write(TimeofDay)  
</script>