http://webdeveloperswall.com/buddypress/load-more-activities-on-scroll

Buddypress load more activities on scroll

/**
 * automatically load activities when user scrolls down - like facebook
 * @author: @webdwall - http://webdeveloperswall.com/buddypress/load-more-activites-on-scroll
**/
jQuery(window).load(function(){
	/*
	 * 1. bind event on page scroll
	 * 2. check if user has reched near to the bottom of activity stream( ScrollTop and pageheight etc..)
	 * 3. load the new content
	 * 4. update the pageheight etc..
	*/
	var e_a_al_inAction = false;
	/* first we will load new content when user has scrolled down 80% of the total height.
	 * next time when user has scrolled 85%.. next time 90% and so on till 95%
	 * Why the extra pain? ... Save server resources :) 
	*/
	var e_a_al_factor = 80;
	
	//80% of the height of the document, offset scroll height to start loading new content
	var e_a_al_offset = (jQuery(document).height())*( 0.8 );
	
	jQuery(document).scroll(function(){
		if(jQuery(document).scrollTop() > e_a_al_offset && e_a_al_inAction == false){
			e_a_al_inAction = true;

			jQuery("#content li.load-more").addClass('loading');

			if ( null == jQuery.cookie('bp-activity-oldestpage') )
				jQuery.cookie('bp-activity-oldestpage', 1, {
					path: '/'
				} );

			var oldest_page = ( jQuery.cookie('bp-activity-oldestpage') * 1 ) + 1;

			jQuery.post( ajaxurl, {
				action: 'activity_get_older_updates',
				'cookie': encodeURIComponent(document.cookie),
				'page': oldest_page
			},
			function(response)
			{
				jQuery("#content li.load-more").removeClass('loading');
				jQuery.cookie( 'bp-activity-oldestpage', oldest_page, {
					path: '/'
				} );
				jQuery("#content li.load-more").replaceWith(response.contents);
				
				//reset and setup everything for next load request
				e_a_al_inAction = false;
				e_a_al_factor += 5;
				if( e_a_al_factor>95 ){ e_a_al_factor=95; }
				e_a_al_offset = (jQuery(document).height())*( e_a_al_factor/100 );
				
			}, 'json' );

			return false;
			
		}
	});
});