Restriction on number of opened tabs

Question

Restriction on number of opened tabs

2.4k views Asked by user752590 At 09 June 2015 at 08:21

There are some links on web-page.

On right click there is option of 'open link in new tab'(browser option).

I want to restrict user for not opening more that two tabs? How can i do this?

<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<ul>
<li><a href="http://localhost:8080/struts_tab/abcForm1.action" oncontextmenu="return false;"><span>First Click[Right Click disabled]</span></a></li>
<li><a href="http://localhost:8080/struts_tab/defForm2.action"><span>Second clieck[Not more than 2 tabs]</span></a></li>
</ul>
</body>
</html>

Original Q&A

There are 1 answers

**Andrea Ligios** · Accepted Answer · 2015-06-09 09:12:33

You can't restrict the user from opening a new tab.
_{(This reminds me the old pop-ups with no buttons, no address bar, but still responding to backspace and other events)}

You can however make your app recognize the attempt of opening a third tab, and load a different result like an error message, for example:

Maximum open tabs limit reached. Please use no more than two tabs concurrently. close this tab

To do this, you can use HTML5 sessionStorage.
_{Note: Web Storage (sessionStorage and localStorage) is supported on every browser nowadays.}

sessionStorage

This is a global object (sessionStorage) that maintains a storage area that's available for the duration of the page session. A page session lasts for as long as the browser is open and survives over page reloads and restores. Opening a page in a new tab or window will cause a new session to be initiated.

Then you can

if not present in sessionStorage, generate an unique token in JSP, and put it in sessionStorage,

$(function(){
    // Read the ID. If it's null, this is a new tab: 
    // generate the ID and store it for later.
    var tabId = sessionStorage.getItem("tabId");
    if (tabId == null){
        tabId = Math.random();
        sessionStorage.putItem("tabId",tabId);
    }

send it back to the action

    // Add the ID to the form (as hidden field), 
    // so it will be posted back in next submission.
    $('<input>').attr('type'  , 'hidden')
                .attr('name'  , 'tabId')
                .attr('value' , tabId)
    .appendTo('form');
});

, maybe to a setter in a BaseAction, extendend by the other actions, and read by prepare(), or much better in an Interceptor;

put it in a collection checking that it doesn't contain already two elements, otherwise return the error result, that should be mapped globally:

public String intercept(ActionInvocation actionInvocation) throws Exception {
    Action action = (Action) actionInvocation.getAction();
    if(action instanceof LimitedTabsAware){ //interface to identify special actions
        ActionContext context = actionInvocation.getInvocationContext();
        Map<String, String[]> request = ((HttpServletRequest) 
                            context.get(StrutsStatics.HTTP_REQUEST)).getParameterMap();

        if (request.containsKey("tabId")){              
            String tabId = (String) request.get("tabId")[0];
            List<String> openTabs = context.getSession().get("OPEN_TABS_KEY");

            if (openTabs.contains(tabId)){
                return actionInvocation.invoke();                   
            } else if (openTabs.size()>=2){
                return "tabLimitExceeded"; // global result
            } else {
                openTabs.add(tabId);
                context.getSession().put("OPEN_TABS_KEY", openTabs);
                return actionInvocation.invoke();
            }

        } else {
            throw new IllegalArgumentException("There is no tabId in this request.");
        }
    } else {
        return actionInvocation.invoke();
    }
}

Then you should find a way to recognize when a tab get closed (to free one slot), by either:

timizing the period of validity of the elements in your collection (if you don't use a tab for some time, the session expires, and so must do the token in the collection)
otherwise, putting a javascript AJAX timer in your page (eg. every 30 seconds), that send a keep-alive signal to an action to refresh the validity of the element. If the tab get closed, the signal is not sent anymore.

TechQA.

Restriction on number of opened tabs

There are 1 answers

sessionStorage

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