Disable browser back button once the user get login in JSF pages
===

I have used tiles in Spring web flow.This is my standard jsf file.

standard.xhtml

          

          <f:view contentType="text/html">

       <h:head >
	<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
	<title>Nagra Employee Leave Application</title>
	<link rel="stylesheet" href="${request.contextPath}/styles/blueprint/screen.css" type="text/css" media="screen, projection" />
	<link rel="stylesheet" href="${request.contextPath}/styles/blueprint/print.css" type="text/css" media="print" />
	
	<link rel="stylesheet" href="${request.contextPath}/styles/le-frog/jquery-ui-1.8.2.custom.css" type="text/css" media="screen" />
	<ui:insert name="headIncludes"/>
	<style>
	
	</style>
      </h:head>
       <h:body  style="background:#343433" >
       <div class="container" style="background:white;">
	

		<a href="#{request.contextPath}"><img src="${request.contextPath}/images/rubon1.jpg" height="200" width="950" alt="Spring Travel"/></a>
		
	
	<div>
		<div id="local" class="span-4 colborder" style="padding-top: 20px;
        padding-left: 21px;">
			<h3>Nagra Vision</h3>
			<ui:insert name="notes"/>
		</div>
		<div class="span-19 last" style="width: 720px;">
			<ui:insert name="content"/>
		</div>
	</div>
	
	<div>
		<a href="http://www.nagra.com">
			<img src="${request.contextPath}/images/nagra_footer.png" alt="Powered by Nagra-India" />
		</a>
	</div>
     </div>
     </h:body>
   </f:view>
   </html>

Login.xhtml

      
     <ui:composition xmlns="http://www.w3.org/1999/xhtml"
	xmlns:ui="http://java.sun.com/jsf/facelets"
	xmlns:h="http://java.sun.com/jsf/html"
	xmlns:f="http://java.sun.com/jsf/core"
	xmlns:p="http://primefaces.org/ui"
	template="/WEB-INF/layouts/standard.xhtml">
	
	<ui:define name="content">
		<h:form style="margin-top:10px;">
			<div>
				<h:outputLabel for="username">Username:    </h:outputLabel>
				<h:inputText id="username" value="#{userInfo.username}">          </h:inputText>
			</div>
			<div>
				<h:outputLabel for="password">Password:    </h:outputLabel>
				<h:inputSecret id="password" value="#{userInfo.password}">
				</h:inputSecret>
			</div>
			<div>

				<h:selectBooleanCheckbox id="leavetype"
					value="#{userInfo.loginperson}">
					<f:selectItems value="#{referenceData.loginPersonOptions}" />
				</h:selectBooleanCheckbox>
				<h:outputLabel for="password">Select you are a manager</h:outputLabel>
			</div>

			<div>
				<p:commandButton id="Signin" action="click" value="Sign In"
					style="margin-left:80px;" />
			</div>
		</h:form>
	</ui:define>
</ui:composition>


mainpage.xhtml

     
     <ui:composition xmlns="http://www.w3.org/1999/xhtml"
	xmlns:ui="http://java.sun.com/jsf/facelets"
	xmlns:h="http://java.sun.com/jsf/html"
	xmlns:f="http://java.sun.com/jsf/core"
	xmlns:p="http://primefaces.org/ui"
	template="/WEB-INF/layouts/standard.xhtml">
	<ui:define name="notes">
		<h:outputLabel for="employee">${loginperson.username}</h:outputLabel>
		<h:form>
		<div>	<h:commandLink value="Sick Leave" action="sickleave" id="sickleave" /></div>
		<div>	<h:commandLink value="Paid off Leave" action="paidleave" id="paidleave" /></div>
		<div>	<h:commandLink value="Logout" action="logout" id="logout" /></div>
		</h:form>



	</ui:define>
	<ui:define name="content">
		 <h2 style="font-size: 16px; font-weight: bold; margin-top: 100px;">Available
			Leave</h2>



	
		<h:dataTable value="#{leaveavailable}" var="a"
			styleClass="order-table" headerClass="order-table-header"
			rowClasses="order-table-odd-row,order-table-even-row"
			columnClasses="order-table-odd-column,order-table-even-column">
			<h:column>
				<f:facet name="header">
    				Sick Leave
    			</f:facet>
    				#{a.totalSickLeave}
    		</h:column>
			<h:column>
				<f:facet name="header">
    				Paidoff Leave
    			</f:facet>
    				#{a.totalPaidoffLeave}
    		</h:column>
		</h:dataTable>



	</ui:define>
</ui:composition>



here once the user login in the user will see the mainpage.xhtml.After the user getting into the mainpage,if he press the back button of the browser it takes me to the login page.So I need to disable the back button.I do no where to add the javascript code to disable the browser back button.Whether I have to add in mainpage.xhtml or in standard.xhtml.

 What java script i have to add to disable the back button