ajax-append-auto.js

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define(['jquery', 'page/components/list/ajax-append'], function ($) {
    
    var debounceTimeout;
    
    // Returns a function, that, as long as it continues to be invoked, will not
    // be triggered. The function will be called after it stops being called for
    // N milliseconds. If `immediate` is passed, trigger the function on the
    // leading edge, instead of the trailing.
    function debounce(func, wait, immediate) {
        return function() {
            var context = this, args = arguments;
            var later = function() {
                debounceTimeout = null;
                if (!immediate) func.apply(context, args);
            };
            var callNow = immediate && !timeout;
            clearTimeout(debounceTimeout);
            debounceTimeout = setTimeout(later, wait);
            if (callNow) func.apply(context, args);
        };
    };
    
    function checkScroll() {
        var $elem = $('.elgg-list-container-ajax-append-auto .elgg-pagination-next > a:visible');
        if (!$elem.length) {
            return;
        }
        
        var docViewTop = $(window).scrollTop();
        var docViewBottom = docViewTop + $(window).height() + 500; // make screen larger to prevent button from coming into view

        var elemTop = $elem.offset().top;
        var elemBottom = elemTop + $elem.height();

        if ((elemBottom <= docViewBottom) && (elemTop >= docViewTop)) {
            $elem.click();
        }
    };
    
    $(document).off('scroll.ajax-append-auto');
    $(document).on('scroll.ajax-append-auto', debounce(checkScroll, 100));
});