I have a java script form in a website, that outputs some results -a silly simple mathematical operation or subtraction of dates.
I need these results to "remember" the visit so the div and the results
show when the user re-loads the page.
How can I achieve this?? It's my first time with facing a situation like this...
Note: its not a logged user!! but a non-logged visit..
http://goo.gl/OHQmpb
You can use localStorage.
Store the values in it by specifiying a key:
localStorage.setItem('key','value');
And, you can get the value by:
var value = localStorage.getItem('key');
HTML5 Web storage is the best option in your case.
Exact definition:
So what is HTML5 Storage? Simply put, it’s a way for web pages to
store named key/value pairs locally, within the client web browser.
Like cookies, this data persists even after you navigate away from the
web site, close your browser tab, exit your browser, or what have you.
Unlike cookies, this data is never transmitted to the remote web
server (unless you go out of your way to send it manually).
With HTML5, web pages can store data locally within the user's browser.
// Store it in object
localStorage.setItem("form attributes", "form values");
// Retrieve from object
localStorage.getItem("form attributes");
HTML5 Local Storage aka Web Storage can store values without maintaining a server side session. See this example:
function calculate(){
return 'some value';
}
window.onload = function(){
// submit handler for the form, store in local storage
document.getElementById("myform").onsubmit = function(){
localStorage.setItem('calcResult', calculate());
return false;
};
// load the value if present
var result = localStorage.getItem('calcResult');
if(result != null){
// show in div
document.getElementById("mydiv").innerHTML = result;
}
}
Related
var userInfo = [];
var myCostum;
//documentgetElementById("registerForm");
document.getElementById("registerForm").addEventListener("click", function ()
{
//var register = document.querySelector('#registerForm');
var name = document.querySelector('#fN').value;
var lastN = document.querySelector('#lN').value;
var userName = document.querySelector('#uN').value;
var passwrd = document.querySelector('#pS').value;
userInfo.push([name,lastN,userName,passwrd]);
localStorage.setItem("myCostum", JSON.stringify(userInfo));
});
I am using separate files for j, my website has a navigation bar with home,register,login,about me and shopping car. this code works fine if i register more than one user, i can see the users in the local storage on all pages and i can even sign in. the problem is when i go to register again and register a new user the users that i reister before are deleted and replaced by the new user. also if i go to home page i can an error (Uncaught TypeError: Cannot read property 'addEventListener' of null
at even-listener.js:9). i just do not had idea why register page seems to work but the rest not. I had another code using onclick in html but the same it does not give any error in any page but the users gone when i register new one after navigating through my pages. this is the first time using localStorage and i do not can i do or if it is normal. i am stack and i need to keep adding more code but i want to solve this problem first.
Lots of things going on here, but let me start from the basics.
1st never use local storage for sensitive information such as usernames and passwords. There's a lot of sites that copy local storages and send it to malicious people.
2nd you could in theory use session storage limited to the tab, but you still could be under the danger of xss.
3rd when the browser closes, all your data will be lost from the local storage anyway
As for your code. Your user info, should not be initiated as empty. You must get the previous value from local storage and push to it. Otherwise you are just overriding the previous value.
var userInfo = JSON.parse(localStorage.getItem('myCustom'));
I have some javascript, in which i need either cookies or localstorage to ensure variables aren't lost.
I'm a beginner and i'm not sure which is best to use, but i know both do sort of the same thing.
Basically, i need whatever the javascript is doing to be stored and even when user logs out / logs in, between any amount of days this is still being saved.
Can someone help?
<script>
$(document).ready(function() {
$("input").click(function(e) {
e.preventDefault();
var $challenge_div = $(this).parent().parent();
$challenge_div.data("finish", "false");
$challenge_div.removeClass("show").addClass("hide");
var $challenge_list = $("div[class='hide']");
$.each($challenge_list, function() {
var new_challenge = $(this);
if (new_challenge.data("finish") == false) {
new_challenge.removeClass("hide").addClass("show");
return false;
}
});
if ($("div[class='show']").length == 0) {
$("#message p").html("You finished all your challenges !");
}
});
});
</script>
I'm a beginner and i'm not sure which is best to use, but i know both do sort of the same thing.
Actually, they do very different things.
Cookies are for sending information back and forth between the server and client on every HTTP request.
Web storage is for storing information in the client (only).
For your use case, web storage would be the right thing to use, since you only want the information client-side. It also has a reasonable API (unlike cookies). You can store a string:
localStorage.setItem("key", "value");
// or
localStorage.key = "value"; // See warning below
// or
localStorage["key"] = "value"; // See warning below
(I'd recommend using the setItem method instead of directly assigning to a property on localStorage, so there's no chance of your conflicting with any of localStorage's methods!)
...and get it back later, even in the user left the page entirely and came back:
var x = localStorage.getItem("key");
// or
var x = localStorage.key; // See warning above
// or
var x = localStorage["key"]; // See warning above
console.log(x); // "value"
And remove it if you want:
localStorage.removeItem("key");
Often, it makes sense to use JSON to store your client-side information, by using some kind of settings object and storing it by converting it to JSON:
localStorage.setItem("settings", JSON.stringify(settings));
...and using JSON.parse when getting it (back):
var settings = JSON.parse(localStorage.getItem("settings"));
if (!settings) {
// It wasn't there, set defaults
settings = {/*...*/};
}
I'm not sure which is best to use, but I know both do sort of the same thing.
Not really. A key difference in Cookies and Local Storage is that cookies will be sent along with every server request you make.[1]
Requesting some data using AJAX, cookies will be included in the request.
Navigating to a new page, cookies will be included in the request.
So the disadvantage is that you are transferring additional data to the server every time you make a request. More so if you are storing a lot of data into the cookies.
Local storage is merely kept in the browser (until you clear it explicitly), but it is not sent along with every request.
The decision is simple, if you require that data available to the server with request parameters, you should use cookies, else use local storage.
One more thing, from what you are saying, it seems like you intend to store the user's progress in a game. Keep in mind that both cookie and local storage are accessible to the user. So they can tamper with that data if they want.
If it is critical to prevent user's from changing the data, you must store the data on the server instead.
Do read: JavaScript: client-side vs. server-side validation
[1]. This may not be entirely true with HTTP2 but that's a different topic.
So I have one HTML page which consists of a bunch of form elements for the user to fill out. I push all the selections that the user makes into one global variable, allTheData[] inside my only Javascript file.
Then I have a 2nd HTML page which loads in after a user clicks a button. This HTML page is supposed to take some of the data inside the allTheData array and display it. I am calling the function to display allTheData by using:
window.onload = function () {
if (window.location.href.indexOf('Two') > -1) {
carousel();
}
}
function carousel() {
console.log("oh");
alert(allTheData.toString());
}
However, I am finding that nothing gets displayed in my 2nd HTML page and the allTheData array appears to be empty despite it getting it filled out previously in the 1st HTML page. I am pretty confident that I am correctly pushing data into the allTheData array because when I use alert(allTheData.toString()) while i'm still inside my 1st HTML page, all the data gets displayed.
I think there's something happening during my transition from the 1st to 2nd HTML page that causes the allTheData array to empty or something but I am not sure what it is. Please help a newbie out!
Web Storage: This sounds like a job for the window.sessionStorage object, which along with its cousin window.localStorage allows data-as-strings to be saved in the users browser for use across pages on the same domain.
However, keep in mind that they are both Cookie-like features and therefore their effectiveness depends on the user's Cookie preference for each domain.
A simple condition will determine if the web storage option is available, like so...
if (window.sessionStorage) {
// continue with app ...
} else {
// inform user about web storage
// and ask them to accept Cookies
// before reloading the page (or whatever)
}
Saving to and retrieving from web storage requires conversion to-and-from String data types, usually via JSON methods like so...
// save to...
var array = ['item0', 'item1', 2, 3, 'IV'];
sessionStorage.myApp = JSON.stringify(array);
// retrieve from...
var array = JSON.parse(sessionStorage.myApp);
There are more specific methods available than these. Further details and compatibility tables etc in Using the Web Storage API # MDN.
Hope that helps. :)
I'm making a little client-side web app for MagicCardMarket.eu. It's just javascript and html. The user has to log in using his username and apikey, though I was wondering what's the best way to save these between sessions?
It's the first time I make this kind of web app. It's also the first time I use anything like this apikey, so I wasn't sure what to Google.
Thanks!
You can use sessionStorage.
sessionStorage.setItem('key','value');
var value = sessionStorage.getItem('key');
So what is it?
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.
use session storage. It stores values as key, value pairs.
To set the value to session use
sessionStorage.name = "Use Name";
sessionStorage.APIKey = "Use APIKey";
To Get the values from session storage:
var name = sessionStorage.name;
var APIKey = sessionStorage.APIKey;
Note: Name/value pairs are always stored as strings. Remember to convert them to another format when needed!
I need to be able to retrieve the list of request URLs that are displayed in the browser console, i.e: GET http://mydomain.com/index.php?p=1&curr=GBP&cat=Food. 200. Users can click around my app and apply different filters and scrolls through pages and I need some way of tracking this so that I always know what data has already been loaded for that users session.
I had thought about using PHPs $_SERVER['REQUEST_URI'] and saving them in a session but then I don't know how I would access this session from my JQuery as its JQuery that constructs the URLs.
Has anyone any idea how I can access this data from the console? Is this possible? If not can anyone suggest a workaround?
The PHP / JQuery mess I have so far:
<?php
session_start();
//keep track of requests.
if (!isset($_SESSION['requests'])) {
$_SESSION['requests'] = array();
} else {
if (!in_array( $_SERVER['REQUEST_URI'], $_SESSION['requests'])) {
$_SESSION['requests'][] = $_SERVER['REQUEST_URI'];
}
}
$requests = json_encode($_SESSION['requests']);
print_r($_SESSION['requests']);
print_r($requests); //these both have values
?>
//further down the page is the javascript
$('.filter a').click(function(e) {
var $this = $(this);
var $optionSet = $this.parents('.option-set');
var group = $optionSet.attr('data-filter-group');
filters[ group ] = $this.attr('data-filter-value');
//***more code for filtering etc******/
var paginate_url = $('.paginate a').attr('href');
//THIS IS PART I CANNOT GET WORKING
var visited_urls= <?=$requests?>;
//console.log($.parseJSON(visited_urls));
console.log(visited_urls); //is always empty
var pageno = ''; //somehow check to see if the URL that has been clicked exists int he requests array, if so get the page number and increment.
var next_url = UpdateQueryString(paginate_url, pageno, group, encodeURIComponent(filter_qry));
I'm not completely sure what you're trying to do but I think you can skip the PHP and just use JavaScript and sessionStorage: https://developer.mozilla.org/en-US/docs/Web/Guide/API/DOM/Storage#sessionStorage or localStorage: https://developer.mozilla.org/en-US/docs/Web/Guide/API/DOM/Storage#localStorage (depending on how persistent you want the data to be)
For example if I want to listen for all clicks on 'a' tags and track whether those hrefs have been visited (and how many times)
$(document).ready(function() {
// store an empty object in session storage when the page loads
sessionStorage.visited = JSON.stringify({});
});
$('a').on('click', function() {
var storage = JSON.parse(sessionStorage.visited),
href = $(this).attr('href');
// when we get a click check to see if this has been clicked before
if (!storage[href]) {
// if not save it and set the count to 1
storage[href] = 1;
} else {
// otherwise increment the count
storage[href]++;
}
sessionStorage.visited = JSON.stringify(storage);
});
If you want to save the urls from your ajax calls the same principle applies but listen for the ajaxSuccess event and store the url from the request in the callback: http://api.jquery.com/ajaxSuccess/
This is my suggestion:
PHP + Javascript Implementation:
In PHP, use $_GET['curr'] and $_GET['cat'] to retrieve the arguements from the URL.
Use $_SESSION['curr'] = $_GET['curr']; to save them per the session.
On your Javascript/jQuery use var curr = "<?php echo $_SESSION['curr']; ?>" to make the PHP session variables available to your Javascript.
Basically the key to have a good PHP/Javascript persistent memory is that you can set PHP content into a Javascript variable by using:
var x = <?php echo '123';?>;
console.log(x); //output '123' to Javascript console
If you need to have a list of all visited urls, you can save them in a PHP array and transfer it to Javascript as well.
On PHP side:
if (!isset($_SESSION['visited'])) $_SESSION['visited'] = array();//initialize the array if doesn't exist
if (!inarray( $_SERVER['REQUEST_URI'], $_SESSION['visited']) { //check if current URL is not in array
$_SESSION['visited'][] = $_SERVER['REQUEST_URI'];//push it to the array
}
On Client side:
//this will convert the PHP array to a Javascript array using json_encode
var visited_urls= <?php echo json_encode($_SESSION['visited']); ?>;
Don't forget to use session_start() on every page you need the session variables.
Javascript Only Implementation:
Use localStorage and keep everything on the client side.
EDIT: Note that localStorage is only supported in IE8 and up, so if versions prior to IE8 must be supported, you will need to use Cookies instead of localStorage.
$(document).ready(function() {
var urls = JSON.parse(localStorage["visited"]) || [];//get the visited urls from local storage or initialize the array
if (urls.indexOf(document.URL) == -1) {//if current url does not exist in the array
urls.push(document.URL);//add it to the array
localStorage["visited"] = JSON.stringify(urls);//save a stringifyed version of the array to local storage
}
});
Hope this helps!
It's unclear what you want to achieve with this feature. You state:
Users can click around my app and apply different filters and scrolls through pages and I need some way of tracking this so that I always know what data has already been loaded for that users session.
What do you want to achieve with this, why isn't the browser's cache enough for you?
My idea for a solution would be to sync server session array with an object inside the Browser via some sort of WebSocket (http://en.wikipedia.org/wiki/WebSocket).
UPDATE2:
It is possible to use localStorage as cache storage as Abel Melquiades Callejo suggests and then read from it bypassing HTTP requests. I would choose what content to save to that cache differently, no server involved:
add a custom attribute data-* to every HTML element you want cached (http://html5doctor.com/html5-custom-data-attributes/);
make a querySelectorAll (https://developer.mozilla.org/en-US/docs/Web/API/Document.querySelectorAll) for all HTML elements with that attribute;
storing and retrieving documents from localStorage should be easy now, you need a convention for naming files for easy finding;
storing images implies doing a base64 transformation which increases the size of the data by 34% (image with 64kb will take 86kb in localStorage).
you need a way to find when data in localStorage is obsolete and you need to make requests to the server (perhaps another data-age attribute to specify when should it expire).
However, this localStorage solution is limited to a small amount of data, see this issue https://github.com/RemoteStorage/remoteStorage.js/issues/144. So, although I now see that what you are asking is possible, because of this size limitation to localStorage, I strongly recommend the solutions in my UPDATE1, below.
UPDATE1: The point is that caching mechanisms are incredibly complex. A better alternative would be to use the default browser caching mechanisms:
1. HTML5 cache manifest
Go offline with application cache
http://html5doctor.com/go-offline-with-application-cache/
LET’S TAKE THIS OFFLINE http://diveintohtml5.info/offline.html
Using the application cache
https://developer.mozilla.org/en/docs/HTML/Using_the_application_cache
A Beginner's Guide to Using the Application Cache http://www.html5rocks.com/en/tutorials/appcache/beginner/
2. Server's response headers to HTTP requests
Optimize caching - Leverage browser caching
https://developers.google.com/speed/docs/best-practices/caching#LeverageBrowserCaching
HTTP Caching FAQ https://developer.mozilla.org/en/docs/HTTP_Caching_FAQ