jQuery load more data on scroll

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夕颜 2020-11-22 10:44

I am just wondering how can i implement more data on scroll only if the div.loading is visible.

Usually we look for page height and scroll height, to see if we need

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  • 2020-11-22 11:21

    The accepted answer of this question has some issue with chrome when the window is zoomed in to a value >100%. Here is the code recommended by chrome developers as part of a bug i had raised on the same.

    $(window).scroll(function() {
      if($(window).scrollTop() + $(window).height() >= $(document).height()){
         //Your code here
      }
    });
    

    For reference:

    Related SO question

    Chrome Bug

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  • 2020-11-22 11:26

    I spent some time trying to find a nice function to wrap a solution. Anyway, ended up with this which I feel is a better solutions when loading multiple content on a single page or across a site.

    Function:

    function ifViewLoadContent(elem, LoadContent)
        {
                var top_of_element = $(elem).offset().top;
                var bottom_of_element = $(elem).offset().top + $(elem).outerHeight();
                var bottom_of_screen = $(window).scrollTop() + window.innerHeight;
                var top_of_screen = $(window).scrollTop();
    
                if((bottom_of_screen > top_of_element) && (top_of_screen < bottom_of_element)){
                if(!$(elem).hasClass("ImLoaded"))   {
                    $(elem).load(LoadContent).addClass("ImLoaded");
                }
                }
                else {
                   return false;
                }
            }
    

    You can then call the function using window on scroll (for example, you could also bind it to a click etc. as I also do, hence the function):

    To use:

    $(window).scroll(function (event) {
            ifViewLoadContent("#AjaxDivOne", "someFile/somecontent.html"); 
    
            ifViewLoadContent("#AjaxDivTwo", "someFile/somemorecontent.html"); 
        });
    

    This approach should also work for scrolling divs etc. I hope it helps, in the question above you could use this approach to load your content in sections, maybe append and thereby dribble feed all that image data rather than bulk feed.

    I used this approach to reduce the overhead on https://www.taxformcalculator.com. It died the trick, if you look at the site and inspect element etc. you can see impact on page load in Chrome (as an example).

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  • 2020-11-22 11:34

    In jQuery, check whether you have hit the bottom of page using scroll function. Once you hit that, make an ajax call (you can show a loading image here till ajax response) and get the next set of data, append it to the div. This function gets executed as you scroll down the page again.

    $(window).scroll(function() {
        if($(window).scrollTop() == $(document).height() - $(window).height()) {
               // ajax call get data from server and append to the div
        }
    });
    
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  • 2020-11-22 11:37

    If not all of your document scrolls, say, when you have a scrolling div within the document, then the above solutions won't work without adaptations. Here's how to check whether the div's scrollbar has hit the bottom:

    $('#someScrollingDiv').on('scroll', function() {
        let div = $(this).get(0);
        if(div.scrollTop + div.clientHeight >= div.scrollHeight) {
            // do the lazy loading here
        }
    });
    
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  • 2020-11-22 11:37

    You question specifically is about loading data when a div falls into view, and not when the user reaches the end of the page.

    Here's the best answer to your question: https://stackoverflow.com/a/33979503/3024226

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  • 2020-11-22 11:39

    Here is an example:

    1. On scrolling to the bottom, html elements are appeneded. This appending mechanism are only done twice, and then a button with powderblue color is appended at last.

    <!DOCTYPE html>
    <html>
    <head>
        <title>Demo: Lazy Loader</title>
        <script src="https://code.jquery.com/jquery-3.2.1.min.js"></script>
        <style>
            #myScroll {
                border: 1px solid #999;
            }
    
            p {
                border: 1px solid #ccc;
                padding: 50px;
                text-align: center;
            }
    
            .loading {
                color: red;
            }
            .dynamic {
                background-color:#ccc;
                color:#000;
            }
        </style>
        <script>
    		var counter=0;
            $(window).scroll(function () {
                if ($(window).scrollTop() == $(document).height() - $(window).height() && counter < 2) {
                    appendData();
                }
            });
            function appendData() {
                var html = '';
                for (i = 0; i < 10; i++) {
                    html += '<p class="dynamic">Dynamic Data :  This is test data.<br />Next line.</p>';
                }
                $('#myScroll').append(html);
    			counter++;
    			
    			if(counter==2)
    			$('#myScroll').append('<button id="uniqueButton" style="margin-left: 50%; background-color: powderblue;">Click</button><br /><br />');
            }
        </script>
    </head>
    <body>
        <div id="myScroll">
            <p>
                Contents will load here!!!.<br />
            </p>
            <p >This is test data.<br />Next line.</p>
            <p >This is test data.<br />Next line.</p>
            <p >This is test data.<br />Next line.</p>
            <p >This is test data.<br />Next line.</p>
            <p >This is test data.<br />Next line.</p>
            <p >This is test data.<br />Next line.</p>
            <p >This is test data.<br />Next line.</p>
            <p >This is test data.<br />Next line.</p>
            <p >This is test data.<br />Next line.</p>
            <p >This is test data.<br />Next line.</p>
            <p >This is test data.<br />Next line.</p>
            <p >This is test data.<br />Next line.</p>
            <p >This is test data.<br />Next line.</p>
            <p >This is test data.<br />Next line.</p>
            <p >This is test data.<br />Next line.</p>
            <p >This is test data.<br />Next line.</p>
            <p >This is test data.<br />Next line.</p>
            <p >This is test data.<br />Next line.</p>
            <p >This is test data.<br />Next line.</p>
            <p >This is test data.<br />Next line.</p>
            <p >This is test data.<br />Next line.</p>
            <p >This is test data.<br />Next line.</p>
        </div>
    </body>
    </html>

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