functions.php

function smoothscroll_script() { ?>
	<script>
	jQuery(document).ready(function($) {

		$('a[href^="#"][href!="#"], .smoothscroll, .smoothscroll a').click(function(e) {
			e.preventDefault();
			e.stopPropagation();
			var url = $(this).attr('href'),
				hash = url.substring(url.indexOf('#'));

			scrollTo(hash);



	    });

	});

	jQuery(window).load(function($) {
		if (window.location.hash)
	        scrollTo(window.location.hash);
	});

	function scrollTo(hash) {

		var offset = jQuery(hash).offset().top,
			headerHeight = 50,
			wpAdminBarHeight = jQuery('html').css("margin-top").replace(/[^-\d\.]/g, '');

		jQuery('html, body').stop().animate({
				scrollTop: (offset - headerHeight - wpAdminBarHeight)
		    }, 1500,'easeInOutExpo', function() { window.location.hash = "" + hash; });


	}
	</script>
<?php
}

add_action( 'wp_footer', 'smoothscroll_script' );