CODEWITHSUNDEEP
javascriptphpjquerysession
proPhet
proPhet

Reputation: 1228

Save jquery's $(window).scrollTop() as PHP $_SESSION['scroll_pos'] variable

I am sending post data to a page that runs a MySql statement then returns via a page redirect

header("location: {$_SERVER['HTTP-REFERER']}");

I am trying to use Ajax to send the $(window).scrollTop() value as a $_GET['scroll_pos'] variable like so:

<?php session_start(); ?>

$(document).ready(function(){

    // SET SCROLL SESSION VARIABLE
    $(window).scroll(function(){

        var xmlhttp;

        if( window.XMLHttpRequest ){
            xmlhttp = new XMLHttpRequest();
        } else {
            xmlhttp = new ActiveXObject( 'Microsoft.XMLHTTP' );
        }

        xmlhttp.open('GET', 'script_files/set_scroll_session.php?scroll_pos=' +
          $(window).scrollTop(), true);
        xmlhttp.send();

    });

    // SCROLL TO $_SESSION['scroll_pos'];
    $(window).scrollTop(<?php echo json_encode($_SESSION['scroll_pos']); ?>); // <-- THIS IS NOT FIRING

});

The set_scroll_session.php page saves the $_GET['scroll_pos'] as a $_SESSION['scroll_pos'] variable like so

<?php

    session_start();

    // VARIABLES
    $scroll_pos = $_GET['scroll_pos'];

    $_SESSION['scroll_pos'] = $scroll_pos;

?>

which needs to be called as seen in the above $(document).ready() function.

The window is not scrolling to amount specified in the $_SESSION['scroll_pos'] variable, how come?

Upvotes: 1

Views: 622

Answers (1)

A.O.
A.O.

Reputation: 3763

First, you are already using jquery so I would highly recommend (however, it's not necessary) that you use jquerys built in AJAX method.

https://api.jquery.com/jQuery.ajax/

And the reason it's not working is because you can't echo out a value to be used in javascript like that, you must use AJAX to fetch that value, then set the scroll position.

//WILL NOT WORK!!!!
$(window).scrollTop(<?php echo json_encode($_SESSION['scroll_pos']); ?>);

Or better yet, save the scroll position in a cookie or local storage to avoid an unnecessary call to the server...

Upvotes: 1

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