$(document).ready(function(){
var checkText=$("div#inner-page-banner-container div.ms-rtestate-field").children('div.ms-rtestate-field').html();	

if (checkText==' ' || checkText=='')
{
	var rand_num=randomFromTo(1,3);
	
   $("div#inner-page-banner-container div.ms-rtestate-field").children('div.ms-rtestate-field').html("<img src='/Style Library/Images/en-us/banners/"+rand_num+".jpg'' alt='Page Banner'/>");
}

});

function randomFromTo(from, to){
       return Math.floor(Math.random() * (to - from + 1) + from);
}