AJAX request default

function get_latest_posts() {
		global $post_request_ajax;

		$load_time = $_GET['load_time'];
		$frontpage = $_GET['frontpage'];
		$num_posts = 10; // max amount of posts to load
		$number_of_new_posts = 0;
		$visible_posts = isset( $_GET['vp'] ) ? (array)$_GET['vp'] : array();

		query_posts( 'showposts=' . $num_posts . '&post_status=publish' );
		ob_start();
		while ( have_posts() ) : the_post();
			$current_user_id = get_the_author_meta( 'ID' );

			// Avoid showing the same post if it's already on the page
			if ( in_array( get_the_ID(), $visible_posts ) )
				continue;

			// Only show posts with post dates newer than current timestamp
			if ( get_gmt_from_date( get_the_time( 'Y-m-d H:i:s' ) ) <= $load_time )
				continue;

			$number_of_new_posts++;
			$post_request_ajax = true;

			p2_load_entry( false );
		endwhile;
		$posts_html = ob_get_clean();

		if ( $number_of_new_posts != 0 ) {
			nocache_headers();
			echo json_encode( array(
				'numberofnewposts' => $number_of_new_posts,
				'html' => $posts_html,
				'lastposttime' => gmdate( 'Y-m-d H:i:s' )
			) );
		} else {
			nocache_headers();
			header( 'HTTP/1.1 200 OK' );
			exit;
		}
	}