We could append items on the Masonry container using the appended method.

var $boxes = $('<div class="box"/><div class="box"/><div class="box"/>');
$('#container').append( $boxes ).masonry( 'appended', $boxes );

Please note that in the above example, we have to wrap the new boxes with the jQuery object. This is because the .masonry() call expects an jQuery object in the 2nd parameter.

Done =)

Reference:

• jQuery Masonry – Methods: appended
• StackOverflow – jQuery Masonry and Ajax Append Items?