Loading JS LocalStorage into PHP Variable

Question

In the header of my doc I am defining an email and password. I would like to use local storage. However I am having trouble loading items from localstorage into my php vars.

Here is my code.

<script>
    localStorage.setItem('email', '<?php echo $_SESSION['email'];?>');  
    localStorage.setItem('password', '<?php echo $_SESSION['password'];?>');
</script>

<?php
    $user_email = "<script>document.write(localStorage.getItem('email'));</script>";
    $password = "<script>document.write(localStorage.getItem('password'));</script>";

    define('XOAUTH_USERNAME', $user_email);
    define('XOAUTH_PASSWORD', $password);
?>

<html>
    <head></head>
    <body></body>
</html>

I know that I am setting the localstorage right because I'm checking in chrome and both key and value are correct. I'm just having problems passing the value of the keys into the define() of my php.

Thanks for the help!

XMLHttpRequest. Or perhaps <form> submit. But, an HTTP request is the only way to pass data from the client (JavaScript) to the server (PHP). — Jonathan Lonowski
– Jonathan Lonowski, Commented Jun 6, 2012 at 23:52
I think there's a mixing between client code and server code here as most of PHP programmers used to do. Why not splitting between server (PHP) and client (JavaScript) code? — Maf
– Maf, Commented Jul 9, 2022 at 2:59
Why would you want to read them from local storage (client side) where you already have these in your session (server side) — theking2
– theking2, Commented Nov 25, 2024 at 7:31

GameCharmer · Accepted Answer · 2012-11-27 14:44:12Z

You cannot access localstorage via PHP. You need to write some javascript that sends the localstorage data back to the script.

If you are using jQuery, do something like the following.

set_page.php

<script>
localStorage.setItem('email', '<?php echo $_SESSION['email'];?>');  
localStorage.setItem('password', '<?php echo $_SESSION['password'];?>');
</script>

login_page.php

<script>
var email = localStorage.getItem('email'), password = localStorage.getItem('password');
$.POST('login_response.php', {'email':email,'password':password}, function(data){
  alert('Login Successful.  Redirect to a different page or something here.');
}
</script>

login_response.php

<?
$email = $_POST['email'];
$password = $_POST['password'];
//Handle your login here.  Set session data, etc.  Be sure to sanitize your inputs.
?>

Remember, people can edit what is in their local storage, so never ever trust user input. A crafty intruder could simply start posting data to your login_response.php page as well.

Jo Smo · Accepted Answer · 2016-09-13 05:54:57Z

8

If you just need to save an email and password (small data), then you could use cookies for this, which you can access via PHP and via JavaScript.

How to set a cookie in PHP:

setcookie("TestCookie", $value, time()+3600, "/", "example.com");

How to delete a cookie:

setcookie("TestCookie", $value, time()-3600, "/", "example.com");

How to get a cookie in PHP:

$_COOKIE["TestCookie"]

The last parameter in this example:

setcookie("TestCookie", $value, time()+3600, "/", "example.com", 1);

indicates that the cookie should only be transmitted over a secure HTTPS connection from the client. When set to TRUE, the cookie will only be set if a secure connection exists. On the server-side, it's on the programmer to send this kind of cookie only on secure connection (e.g. with respect to $_SERVER["HTTPS"]).

Source: https://secure.php.net/manual/en/function.setcookie.php

answered Sep 13, 2016 at 5:54

Jo Smo

7,24910 gold badges52 silver badges68 bronze badges

3 Comments

Maf Over a year ago

The question is about LocalStorage. Why are you talking about cookies?

Glen Keybit Over a year ago

@Maf I came here from a google search for php LocalStorage and this answer made me realise its cookies i should be using.

Maf Over a year ago

I also think there's a mixing between client code and server code here as most of PHP programmers used to do.

AbsoluteƵERØ · Accepted Answer · 2017-05-01 20:26:47Z

0

This is errate, do so

<script>
   localStorage.setItem('email', "<?php echo $_SESSION['email'];?>");
   localStorage.setItem('password', "<?php echo $_SESSION['password'];?>");
</script>

edited May 1, 2017 at 20:26

AbsoluteƵERØ

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answered Jun 6, 2012 at 23:46

Sam

2,9701 gold badge20 silver badges26 bronze badges

6 Comments

Chris Olson Over a year ago

Thanks but this doesn't fix the issue.

Sam Over a year ago

You can't get the output of client localstorage var

Sam Over a year ago

define('XOAUTH_USERNAME', $_SESSION['email']); define('XOAUTH_PASSWORD', $_SESSION['password']);

Chris Olson Over a year ago

I would rather it come from the localstorage because that lasts longer.

Sam Over a year ago

You can do ini_set('gc_maxlifetime','3600') for increase the session time

|

Hitendra Khadtare · Accepted Answer · 2021-12-28 06:30:57Z

0

You can access localstorage via PHP. You need to write some javascript that store localstorage value in COOKIE and you can use it using PHP.

<script>
var email = localStorage.getItem("email");
var d = new Date();
d.setTime(d.getTime() + (1*24*60*60*1000));
var expires = "expires="+ d.toUTCString();
document.cookie = 'email' + "=" + email+ ";" + expires + ";path=/";
</script>
<?php 
print_r($_COOKIE['email']);
?>

answered Dec 28, 2021 at 6:30

Hitendra Khadtare

1

Comments

raphie · Accepted Answer · 2022-08-01 18:21:01Z

I'm sorry to say that if you need to transfer the data from a Local Storage to Cookies it beats the purpose of using Local Storage in the first place. You use Local Storage to avoid using Cookies to optimize user experience. And I reiterate, if that's the purpose of using local storage.

Disadvantage of Cookies:

The storage limit of cookies in web browsers is limited to about 4KB.
Cookies are sent with every HTTP request, thereby slowing down the web application performance.

HTML5 Storage - Sitepoint

The best option is to set up your process allowing PHP to handle the Session then from PHP to Local Storage example (using your own script):

<?php
    $user_email = $_SESSION["user_email"];
    $password = $_SESSION["user_password"];

    define('XOAUTH_USERNAME', $user_email);
    define('XOAUTH_PASSWORD', $password);
?>
<script>
    localStorage.setItem('email', '<?=XOAUTH_USERNAME?>');  
    localStorage.setItem('password', '<?=XOAUTH_PASSWORD?>');
</script>

<html>
    <head></head>
    <body></body>
</html>

You will never be able to access user interaction after the page loads, unless you create a JS script to execute an AJAX login as suggested by @GameCharmer. And of course you need to implement good security practices to avoid Cross Scripting (XSS) attacks from user's input.

P.S. You don't need to use the following statement:

<?php echo $user_password; ?>

Even if shorthand setting is set to off or false in php.ini file you can use:

<?=$user_password?>

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