jQuery infinite scroll plugin

jquery.infinite_scroll.js

// Infinite Scroll
jQuery.fn.infiniteScroll = function(options) {
    return $(this).each(function() {
        var el = $(this);
        var settings = jQuery.extend({
                url: null,
                triggerAt: 300,
                page: 2,
                appendTo: '.list',
                container: $(document)
            }, options);
        var req = null;
        var maxReached = false;
        
        var infinityRunner = function() {
            if (settings.url !== null) {
                if  (settings.triggerAt >= (settings.container.height() - el.height() - el.scrollTop())) {
                    // if the request is in progress, exit and wait for it to finish
                    if (req && req.readyState < 4 && req.readyState > 0) {
                        return;
                    }
                    req = $.get(settings.url, 'page='+settings.page, function(data) {
                        if (data !== '') {
                            $(settings.appendTo).append(data);
                            settings.page++;
                        } else {
                            maxReached = true;
                        }
                    }, 'html');
                }
            }
        };
        
        el.scroll(function(e) {
            if (!maxReached) {
                infinityRunner();
            }
        });
        
        // Test initial page layout for trigger
        infinityRunner();
    });
};