I have a situation in my application where the users should are not allowed to open multiple instances of the application in a browser. So we are reading the cookies, if there is a session already opened we alerting the user that they are attempting to open multiple sessions.Some times if the browser crashes for some reason the browser is still having the old cookie and when the user is attempting to open the application again the browser is not allowing the user to login. User has to manually delete the cookie from the browser history. The business doesn't want that process.FYI I am using angularJS
Found the same question in other post but didn't find an answer I want here Can someone please help me out with this. Thanks in advance!
I came up with the following code. But when the application crashes the cookie is still sitting in the browser and not allowing the user to login at all. The only workaround for me now is to delete the cookie manually from the browser and login.
var duplicateApp = false;
function createCookie(name,value,days) {
var expires = "";
if (days) {
var date = new Date();
date.setTime(date.getTime() + (days*24*60*60*1000));
expires = "; expires=" + date.toUTCString();
}
document.cookie = name + "=" + value + expires + "; path=/";
}
function readCookie(name) {
var nameEQ = name + "=";
var ca = document.cookie.split(';');
for(var i=0;i < ca.length;i++) {
var c = ca[i];
while (c.charAt(0)==' ') c = c.substring(1,c.length);
if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
}
return null;
}
function eraseCookie(name) {
createCookie(name,"",-1);
}
window.onload = function(){
var MyAppCount=readCookie("MyApp");
if (MyAppCount > 0) {
duplicateApp = true;
alert("You are attempting to open multiple application sessions.\n\nPlease close any existing application from the web browser before restarting the application.");
var win = window.open("about:blank", "_self"); win.close();
}
else {
duplicateApp = false;
createCookie("MyApp", 1, 1);
window.onunload = function(){
if (duplicateApp == false) eraseCookie("MyApp");
};
}
};
Could you please suggest any changes I have to make to restrict the user to open only single instance of the application.
I would typically handle this on the login page by creating a new session and invalidating the old one when a user logs in again with the correct credentials.
Related
I am new in this AMP. In web I have scenario like below.
Example I have a page with 100 paragraphs content ... For the user first time visit the page displaying only 10 paragraphs of content. then will ask to user email address in input form. after user provide the email address then will display remaining 90 paragraphs content... The same user visit 2nd time that page we displayed the content without asking email.
Implementation Logic in WEB
After user enter the email address we stored the values in cookies.
If the user visit 2nd time based on cookie values we display the content..
So same logic needs to implements the AMP pages.
I design the form in amp and other stuff but struggling to set the cookie values..
The following code I am used in WEB:
function setCookie(name,value,days) {
var expires = "";
if (days) {
var date = new Date();
date.setTime(date.getTime() + (days*24*60*60*1000));
expires = "; expires=" + date.toUTCString();
}
document.cookie = name + "=" + (value || "") + expires + "; path=/";
}
function getCookie(name) {
var nameEQ = name + "=";
var ca = document.cookie.split(';');
for(var i=0;i < ca.length;i++) {
var c = ca[i];
while (c.charAt(0)==' ') c = c.substring(1,c.length);
if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
}
return null;
}
Once user enter the email and submit the form
setCookie('article-page','email','XXXXX');
You can't directly access cookies from within an AMP page. However, you can use the amp-access component to implement this behavior server-side.
You can ignore the login/logout features provided by amp-access. The only thing you need to do is to change the response for the authorization endpoint to either return true or false depending on whether the user has provided an email address. Based on this information you can then adjust the content that is displayed on the page.
You can set cookie from server-side using amp-state with credentials="include" attribute. Add this amp state in your body html:
<amp-state credentials="include" id="myState" src="https://example.com/data-state"></amp-state>
And set cookie from server side from the source url https://example.com/data-state:
$cookie_name = "user";
$cookie_value = "John Doe";
setcookie($cookie_name, $cookie_value, time() + (86400 * 30), "/"); // 86400 = 1day
Or get cookie from server-side:
if(!isset($_COOKIE['user'])) {
echo "Cookie named '" . $cookie_name . "' is not set!";
} else {
echo "Cookie '" . $cookie_name . "' is set!<br>";
echo "Value is: " . $_COOKIE[$cookie_name];
}
I have an epub3 book with 2 pages as well as a Table of Contents Page. I am viewing this book in Apple's Books, their inbuilt epub3 reader, on Mac OSX. The two pages appear side by side. The first page is as follows:
<?xml version="1.0" encoding="UTF-8"?>
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:epub="http://www.idpf.org/2007/ops">
<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=500, height=600"/>
</head>
<body>
<p id="result"></p>
<script>
//<![CDATA[
var current_page = "1";
var other_page = "2";
var t = 0;
setInterval(function() {
var d = new Date();
var storage = localStorage;
storage.setItem("t"+ current_page, d.toLocaleString());
document.getElementById("result").innerHTML = storage.getItem("t"+ current_page) +" "+storage.getItem("t"+ other_page);
}, 1000);
//]]>
</script>
</body>
</html>
and the only thing different in my second page is:
var current_page = "2";
var other_page = "1";
So every second, Page 1 saves the current time to Local Storage as t1, and Page 2 does the same for the value t2. At the same time, both pages are reading both t1 and t2 from Local Storage, before their values are displayed to screen. However in ibooks, Page 1 only manages to display the current value for t2 when the page is reloaded - like when I flip to the Table of Contents and then back to Page 1 and 2 again. With something similar happening for Page 2 with regard to t1.
So at time 21:10:00, Page 1 might display:
08/09/19, 21:09:18 08/09/19, 21:08:58
and Page 2:
08/09/19, 21:09:22 08/09/19, 21:08:01
I also tried using Session Data but Page 1 can't ever read t2 and Page 2 can't read t1. So, this would be displayed instead:
08/09/19, 21:09:18 null
I can think of several applications where it would be very useful for Pages to communicate with each other.
For example, if a video is playing on one page, it would be useful to stop it if a video on another page is started. This would normally be done using Session Storage. This is related to my own use case and the reason I started exploring this problem.
Likewise, if the user is asked on Page 1 to enters the name of the main character of the story, then that entry should appear immediately on Page 2 once it is entered.
Is there any other way for Pages to communicate with each other in epub3 other than Local or Session Storage?
I dont know epub3 and dont have a MAC to test, but here are four possible solutions that come to my mind:
Cookies
It is not as performant as localStorage for that use-case, but if you dont have many options, better that than nothing.
Functions to create, read and delete cookies (Credits to https://stackoverflow.com/a/28230846/9150652):
function setCookie(name,value,days) {
var expires = "";
if (days) {
var date = new Date();
date.setTime(date.getTime() + (days*24*60*60*1000));
expires = "; expires=" + date.toUTCString();
}
document.cookie = name + "=" + (value || "") + expires + "; path=/";
}
function getCookie(name) {
var nameEQ = name + "=";
var ca = document.cookie.split(';');
for(var i=0;i < ca.length;i++) {
var c = ca[i];
while (c.charAt(0)==' ') c = c.substring(1,c.length);
if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
}
return null;
}
function eraseCookie(name) {
document.cookie = name+'=; Max-Age=-99999999;';
}
Usage for your example:
<script>
//<![CDATA[
var current_page = "1";
var other_page = "2";
var t = 0;
setInterval(function() {
var d = new Date();
setCookie("t"+ current_page, d.toLocaleString(), 100); // 100 days
document.getElementById("result").innerHTML = getCookie("t"+ current_page) +" "+getCookie("t"+ other_page);
}, 1000);
//]]>
</script>
BroadcastChannel
BroadcastChannel is a very new functionality, so it might not be supported by the "Books" app. But here is a concept:
<script>
//<![CDATA[
var broadcaster = new BroadcastChannel('test');
var current_page = "1";
var other_page = "2";
var t = 0;
setInterval(function() {
var d = new Date();
// Send message to all other tabs with BroadcastChannel('test')
bc.postMessage({
senderPage: "t"+ current_page,
date: d.toLocaleString()
});
}, 1000);
broadcaster.onmessage = (result) => {
if(result.senderPage == "t"+ other_page) { // If the message is from the other page
// Set HTML to current date + sent Date from other page
var d = new Date();
document.getElementById("result").innerHTML = d.toLocaleString() +" "+result.date;
}
};
//]]>
</script>
Some sort of Backend
If none of the above works, you probably have no other option, than to use some sort of backend, to provide and save the data
If it is just for you, I suggest you to use a free tier of Firebase or MongoDB Atlas, as they both provide quite some value on their free tier.
If you do it with a Backend, it could be done with something like this:
<script>
//<![CDATA[
var current_page = "1";
var other_page = "2";
var lastLocalDate = new Date();
const serverUrl = "http://someUrl.com/endpoint/"
// Gets the latest date of the other page via ajax
function getUpdate() {
var xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState == XMLHttpRequest.DONE) {
// If successful, update HTML
if (xmlhttp.status == 200) {
document.getElementById("result").innerHTML = lastLocalDate.toLocaleString() +" "+xhr.responseText;
}
// Update the date of this page anyways
sendUpdate();
}
};
// GET request with parameter requestingPage, which is the other page
xmlhttp.open("GET", serverUrl, true);
xmlhttp.send(`requestingPage=${other_page}`);
}
// Sends the current date of this page to the webserver
function sendUpdate() {
var xmlhttp = new XMLHttpRequest();
// No need to check if successful, just update the page again
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState == XMLHttpRequest.DONE) {
getUpdate();
}
};
lastLocalDate = new Date();
// POST request with parameters page and date
xmlhttp.open("POST", serverUrl, true);
xmlhttp.send(`sendingPage=${current_page}&data=${lastLocalDate.toLocaleString()}`);
}
// Start with sending an update (so that lastLocalDate is at least sent once to the server)
sendUpdate();
//]]>
</script>
And some methods in your backend that need to look something like this (note that this is not valid code in any language):
#GET
function getDate(requestingPageId)
find latest entry with page.id == requestingPageId
return page.date
#POST
function saveDate(savingPage, savingDate)
store new page element with
page.id = savingPage
page.date = savingDate
And a collection in your database looking like this:
[
{
id: 1,
date: "date"
},{
id: 2,
date: "date"
},{
id: 2,
date: "date"
},{
id: 1,
date: "date"
},
// ...
]
Window References
If the Books app opens the second tab from the first tab, it might be worth to look into:
Window.postMessage()
With its functions:
Window.open()
to open the second tab and get a reference to it
And Window.opener to get a reference to the opener
I have an application that needs to pop a URL based on a Query String sent to it. Unfortunately, we can't insert any javascript into the application itself, but we can insert an iFrame that loads a page running javascript. There is a bug in the application where it loads the content in the iFrame twice within a couple seconds, which results in the URL popping twice.
To resolve this, I decided to set a cookie with an expiration. Before popping, I would check to see if the cookie exists, and if it does, prevent the pop from happening.
Unfortunately, my cookie is not being set. I've read a few threads about Javascript cookies trying to figure this out. The first thing I found is Chrome does not accept cookies from local files, so I set up an IIS server to host the page.
However, the cookie still is not being set. I read this page to make sure my code was correct, and as far as I can tell, it should be correct.
The code for my page is below. Any help would be greatly appreciated.
<html>
<head>
<script type="text/javascript">
var isPopped;
function myFunction() {
alert("Hello! I am an alert box!");
}
function checkCookie() {
var user=getCookie("username");
if (user != "") {
alert("Welcome again " + user);
} else {
user = prompt("Please enter your name:","");
if (user != "" && user != null) {
setCookie("username", user, 30);
}
}
}
function pop() {
var queryString = location.search.substring(1); //Get Query String from URL of iFrame source. The substring(1) strips off the ? and only takes the first substring. This can be modified to take more and the resulting string can be edited with Regular Expressions if more flexibility is required.
var urlToPop = "https://www.google.com/#" + queryString //Set URL to pop.
var recentVisitTrue=getCookie("visitRecent");
if (recentVisitTrue != "") {
isPopped = 1;
} else {
window.open(urlToPop,"_blank");
setCookie("visitRecent", "true");
}
}
function setCookie(cName,cValue) {
var date = new Date();
date.setTime(d.getTime() + 8000000);
var expires = "; expires=" + date.toGMTString();
document.cookie = cName + "=" + cValue + expires + ";path=/";
}
function getCookie(cName) {
var name = cName + "=";
var ca = document.cookie.split(';');
for(var i=0; i<ca.length; i++) {
var c = ca[i];
while (c.charAt(0)==' ') c = c.substring(1);
if (c.indexOf(name) == 0) {
return c.substring(name.length, c.length);
}
}
return "";
}
</script>
</head>
<body onload="pop();">
v0.32
</body>
</html>
Thanks!
I have a site (landing) that when a user enter automatically goes to another site (its a simple redirect using window.location in the index.html).
The problem is when the user click in the back button on the browser, because when the user goes back, come back to the landing redirect, so the user returns be redirected.
How I can make this redirection only one time per user?
I do not know if it's important but the site (landing) is another domain that the domain of the redirection.
Thank you.
Using the cookie solution. Something like this if I understood your needs correctly:
if (getCookie("first_visit") != "true") {
document.cookie = "first_visit=true";
location.href="NEW_URL";
}
//from http://www.w3schools.com/js/js_cookies.asp
function getCookie(cname) {
var name = cname + "=";
var ca = document.cookie.split(';');
for(var i = 0; i <ca.length; i++) {
var c = ca[i];
while (c.charAt(0)==' ') {
c = c.substring(1);
}
if (c.indexOf(name) == 0) {
return c.substring(name.length,c.length);
}
}
return "";
}
I want to link to a page and when the user clicks on the link his username and password are already there for him. However where i am linking too i don't control that pages code.
Is it possible to have my javascript execute there after the user clicks the link?
$("#link").click(function() {
alert( "Handler for .click() called." );
var username = getCookie("username");
var password = getCookie("password");
var usernameTextBox = document.getElementById("j_username");
var passwordTextBox = document.getElementById("j_password");
usernameTextBox.value = username;
passwordTextBox.value = password;
});
See my JSfiddle
You can't actually execute it from another page, you can however use the following.
The best way to do this is with a cookie, storing the username, and pointing to an encrypted file with an encrypted password. But you can store the encrypted password in a cookie too, as long as it's encrypted before putting it in the cookie.
I originally developed this for a function that will keep a user logged in to a page that redirected to a login whenever it is accessed, it will click the button and bring them to the page after the login page.
working example: Will need to be edited to fit exact elements on any page, and run on the page, probally through a property or permission gained through a download or web app etc.
function setCookie(cname, cvalue, exdays) {
var d = new Date();
d.setTime(d.getTime() + (exdays*24*60*60*1000));
var expires = "expires="+d.toUTCString();
document.cookie = cname + "=" + cvalue + "; " + expires;
}
function getCookie(cname) {
var name = cname + "=";
var ca = document.cookie.split(';');
for(var i=0; i<ca.length; i++) {
var c = ca[i];
while (c.charAt(0)==' ') c = c.substring(1);
if (c.indexOf(name) == 0) return c.substring(name.length,c.length);
}
return "";
}
function stayLoggedIn() {
setCookie("logged_in","true",30);
setCookie("username", username,30);
setCookie("password",encryptedPassword,30);
return null;
}
window.onload {
var loggedIn = getCookie("logged_in");
if(loggedIn == true) {
var username = getCookie("username");
var password = getCookie("password");
var usernameTextBox = document.getElementById("username");
var passwordTextBox = document.getElementById("password");
//decrypt password here.
usernameTextBox.value = username;
passwordTextBox.value = password;
}
else {}
}
Explained:
first, we set a function to set a cookie and get one, I took these from here
then, I set the function stayLoggedIn() this sets the cookie with the value of "logged_in" to true, so when the user comes to the page, and window.onload runs it's block, the if statement is triggered, and the username and password fields are filled in.
Then, click(element) is called on the logginButton, this can click on php, or html buttons or submit forms etc. This simulates the button being clicked, and the user logging in.
Also: You need to call the function stayLoggedIn() after the link is clicked (like through a google or firefox extension)