Check when divs have reached the top of the window

div_is_on_top.js

var custom_menu = {

	handle_colors: function(){

			// by default this works with $(window).on('load resize scroll')
			$('.scroller').on('load resize scroll', function(){
				
				var index_item = custom_menu._get_index(),
				class_item = $('.wrapper-milkguard:eq('+index_item+')').data('menu-color')

				$('#trigger').attr('rel', class_item );

			});

	},

	_get_index: function(){
			
		var layout_list = $('.wrapper-milkguard'), // item to check
		scroll_top = $('.scroller').scrollTop(), // by default this works with $('body')
		special_offset = 50; // if we want to customize our offset top when we check the div DEFAULT: 0

		var offset_list;

		// we go through every item list
		for( var i = 0 ; i <= layout_list.length ; i++ ){

			if( $(layout_list[i]).index() > 0 &&
				$(layout_list[i]).offset().top < special_offset &&
				$(layout_list[i-1]).length ){
				offset_list = $(layout_list[i]).offset().top > $(layout_list[i-1]).offset().top ? $(layout_list[i]).index() : 0;

			}

		}

		// If offset it's not defined
		if( typeof offset_list === 'undefined' ) offset_list = 0;

		return offset_list;
	}
}