我会跳过cookies，使用很棒的脚本store.js

只要踢出一个data-lightbox “Add to Lightbox”链接上的属性，并使用图像ID（假设您使用的是jQuery），它很简单：

$( document.body ).on( "click", "a[data-lightbox]",
    function ( ev ) {
        ev.preventDefault();
        var id = $( this ).data( "lightbox" ), list = store.get( "lightbox" );
        if ( list ) {
            if ( $.inArray( id, list ) === -1 )
                list.push( id );    
        } else {
            list = [ id ];
        }

        store.set( "lightbox", list );
    }
);

$( ".download" ).click(
    function ( ev ) {
        ev.preventDefault();
        var list = store.get( "lightbox" );
        if ( list ) {
            var href = window.location.href,
                args = ( href.indexOf( "?" ) !== -1 ? "&" : "?" ) + "download=" + list.join( "," );

            window.location = href + args;
        }
    }
);