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php – how to remember scroll position of page

Posted by: admin July 12, 2020 Leave a comment

Questions:

I am submitting some data to my database then reloading the same page as the user was just on, I was wondering if there is a way to remember the scroll position the user was just on?

How to&Answers:

I realized that I had missed the important part of submitting, so, I decided to tweak the code to store the cookie on click event instead of the original way of storing it while scrolling.


Here’s a jquery way of doing it:

jsfiddle ( Just add /show at the end of the url if you want to view it outside the frames )

Very importantly, you’ll need the jquery cookie plugin.

jQuery:

// When document is ready...
$(document).ready(function() {

    // If cookie is set, scroll to the position saved in the cookie.
    if ( $.cookie("scroll") !== null ) {
        $(document).scrollTop( $.cookie("scroll") );
    }

    // When a button is clicked...
    $('#submit').on("click", function() {

        // Set a cookie that holds the scroll position.
        $.cookie("scroll", $(document).scrollTop() );

    });

});


Here’s still the code from the original answer:

jsfiddle

jQuery:

// When document is ready...
$(document).ready(function() {

    // If cookie is set, scroll to the position saved in the cookie.
    if ( $.cookie("scroll") !== null ) {
        $(document).scrollTop( $.cookie("scroll") );
    }

    // When scrolling happens....
    $(window).on("scroll", function() {

        // Set a cookie that holds the scroll position.
        $.cookie("scroll", $(document).scrollTop() );

    });

});

@Cody’s answer reminded me of something important.

I only made it to check and scroll to the position vertically.

Answer:

(1) Solution 1:

First, get the scroll position by JavaScript when clicking the submit button.

Second, include this scroll position value in the data submitted to PHP page.

Third, PHP code should write back this value into generated HTML as a JS variable:

<script>
var Scroll_Pos = <?php echo $Scroll_Pos; ?>;
</script>

Fourth, use JS to scroll to position specified by the JS variable ‘Scroll_Pos’

(2) Solution 2:

Save the position in cookie, then use JS to scroll to the saved position when page reloaded.

Answer:

Store the position in an hidden field.

<form id="myform">
  <!--Bunch of inputs-->
</form>

than with jQuery store the scrollTop and scrollLeft

$("form#myform").submit(function(){
   $(this).append("<input type='hidden' name='scrollTop' value='"+$(document).scrollTop()+"'>");

   $(this).append("<input type='hidden' name='scrollLeft' value='"+$(document).scrollLeft()+"'>");
});

Than on next reload do a redirect or print them with PHP

$(document).ready(function(){
   <?php
      if(isset($_REQUEST["scrollTop"]) && isset($_REQUEST["scrollLeft"]))
         echo "window.scrollTo(".$_REQUEST["scrollTop"].",".$_REQUEST["scrollLeft"].")";
   ?>
});

Answer:

Well, if you use _targets in your code you can save that.

Or, you can do an ajax request to get the window.height.

 document.body.offsetHeight;

Then drop them back, give the variable to javascript and move the page for them.

Answer:

To Remember Scroll all pages Use this code

$(document).ready(function (e) {
    let UrlsObj = localStorage.getItem('rememberScroll');
    let ParseUrlsObj = JSON.parse(UrlsObj);
    let windowUrl = window.location.href;

    if (ParseUrlsObj == null) {
        return false;
    }

    ParseUrlsObj.forEach(function (el) {
        if (el.url === windowUrl) {
            let getPos = el.scroll;
            $(window).scrollTop(getPos);
        }
    });

});

function RememberScrollPage(scrollPos) {

    let UrlsObj = localStorage.getItem('rememberScroll');
    let urlsArr = JSON.parse(UrlsObj);

    if (urlsArr == null) {
        urlsArr = [];
    }

    if (urlsArr.length == 0) {
        urlsArr = [];
    }

    let urlWindow = window.location.href;
    let urlScroll = scrollPos;
    let urlObj = {url: urlWindow, scroll: scrollPos};
    let matchedUrl = false;
    let matchedIndex = 0;

    if (urlsArr.length != 0) {
        urlsArr.forEach(function (el, index) {

            if (el.url === urlWindow) {
                matchedUrl = true;
                matchedIndex = index;
            }

        });

        if (matchedUrl === true) {
            urlsArr[matchedIndex].scroll = urlScroll;
        } else {
            urlsArr.push(urlObj);
        }


    } else {
        urlsArr.push(urlObj);
    }

    localStorage.setItem('rememberScroll', JSON.stringify(urlsArr));

}

$(window).scroll(function (event) {
    let topScroll = $(window).scrollTop();
    console.log('Scrolling', topScroll);
    RememberScrollPage(topScroll);
});

Answer:

I had major problems with cookie javascript libraries, most cookie libraries could not load fast enough before i needed to scroll in the onload event. so I went for the modern html5 browser way of handling this. it stores the last scroll position in the client web browser itself, and then on reload of the page reads the setting from the browser back to the last scroll position.

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>

<script type="text/javascript">
$(document).ready(function () {

    if (localStorage.getItem("my_app_name_here-quote-scroll") != null) {
        $(window).scrollTop(localStorage.getItem("my_app_name_here-quote-scroll"));
    }

    $(window).on("scroll", function() {
        localStorage.setItem("my_app_name_here-quote-scroll", $(window).scrollTop());
    });

  });
</script>