How do I declare a PHP variable inside a javascript function?

Question

I want to declare a PHP variable (most preferably a session variable) inside a javascript function.

Here is my html

<form style="text-align:center">
      Service: 
         <select id="selected">
            <option value="">Select Service</option>
            <?php foreach($serves as $serv ) { 
          if($serv['ser'] =='1') { ?>
            <option value="Home Delivery">Home Delivery</option>
            <?php } elseif($serv['ser'] =='2') { ?>
            <option value="Take Away">Take away</option>
            <?php } else  { ?>
            <option value="DinIN">DinIN</option>
            <?php } ?>
            <?php } ?>
         </select>
      </form>

and here if my javascript function but this is not working.

<script type="text/javascript">
    $("#selected").on("change", function () {
        <?php $this->session->data['desired_service'] ?> = this.value;
    });
</script>

Basically on option change, I want a session variable to hold the value of option whichever is selected. Is there any way to do it?

You can't declare a PHP variable in JS. PHP is processed first then JS. You could send an AJAX request to update a PHP session variable. PHP is server side; JS is on the browser/client. — chris85, Oct 28 '15 at 05:23
you cannot directly use JS to change session variables, u can use ajax to run a php script on server which intern change your session for you.. — Hirdesh Vishwdewa, Oct 28 '15 at 05:25
Yes, you'd need to use Ajax. Or you could have JavaScript write a cookie which will be read on the next request to PHP. Or you can submit a form. — Ultimater, Oct 28 '15 at 05:29
Possible duplicate of [What is the difference between client-side and server-side programming?](http://stackoverflow.com/questions/13840429/what-is-the-difference-between-client-side-and-server-side-programming) — chris85, Oct 28 '15 at 05:36

Arpita · Accepted Answer · 2015-10-28T05:37:25.337

You can not set php variable using javascript, use Ajax instead.

Actually php is a server side language and is executed until your webpage if fetching data from server as soon as your page gets completely loaded you loose the access to php variables.

You can achieve this only by AJAX

And to do it with ajax on your current page you can write a function like

$("#selected").on("change", function () {
    $.ajax({
    method: "POST",
    url: "http://url.of/somepage/",
    data: { sessionvalue: this.value }
    })
});

and then on http://url.of/somepage/ you can do

$this->session->data['desired_service'] = $_POST["somepage.php];

Might want to show him how to achieve this with Ajax. – Ultimater Oct 28 '15 at 05:30 — Ultimater, Oct 28 '15 at 05:30

score -1 · Answer 2 · answered Oct 28 '15 at 05:22

-1

try this code:-

<script type="text/javascript">
var <?php echo $this->session->data['desired_service'] ?>;
    $("#selected").on("change", function () {
        <?php echo $this->session->data['desired_service'] ?> = this.value;
    });
</script>

answered Oct 28 '15 at 05:22

Gaurav Srivastava

3,232
3
16
36

1

Yep, he simply forgot the echo. – Ultimater Oct 28 '15 at 05:24
If you're trying to update a PHP session from JavaScript, you need to use Ajax. – Ultimater Oct 28 '15 at 05:27
can you share the link so i could see the javascript error! – Gaurav Srivastava Oct 28 '15 at 05:27
do you need to access the php varialbe after page reload or it only needed for just one time? – Gaurav Srivastava Oct 28 '15 at 05:29

score -3 · Answer 3 · answered Oct 28 '15 at 05:27

-3

<script type="text/javascript">
    // boolean outputs "" if false, "1" if true
    var bool = "<?php echo $bool ?>"; 

    // numeric value, both with and without quotes
    var num = <?php echo $num ?>; // 7
    var str_num = "<?php echo $num ?>"; // "7" (a string)

    var str = "<?php echo $str ?>"; // "A string here"
</script>

answered Oct 28 '15 at 05:27

Raja C

139
1
12

2

the user want to set value of php variable from javascript – Arpita Oct 28 '15 at 05:29

How do I declare a PHP variable inside a javascript function?

3 Answers3