woocommerce/assets/js/frontend/cart.js

jQuery(document).ready(function($) {

	// Shipping calculator
	$(document).on( 'click', '.shipping-calculator-button', function() {
		$('.shipping-calculator-form').slideToggle('slow');
		return false;
	}).on( 'change', 'select#shipping_method, input[name^=shipping_method]', function() {

		var shipping_methods = [];

		$('select#shipping_method, input[name^=shipping_method][type=radio]:checked, input[name^=shipping_method][type=hidden]').each( function( index, input ) {
			shipping_methods[ $(this).data( 'index' ) ] = $(this).val();
		} );

		$('div.cart_totals').block({message: null, overlayCSS: {background: '#fff url(' + wc_cart_params.ajax_loader_url + ') no-repeat center', backgroundSize: '16px 16px', opacity: 0.6}});

		var data = {
			action: 			'woocommerce_update_shipping_method',
			security: 			wc_cart_params.update_shipping_method_nonce,
			shipping_method: 	shipping_methods
		};

		$.post( wc_cart_params.ajax_url, data, function(response) {

			$('div.cart_totals').replaceWith( response );
			$('body').trigger('updated_shipping_method');

		});
	})

	$('.shipping-calculator-form').hide();

});