var config = {
    map: {
        '*': {


          'Magento_Checkout/js/action/select-shipping-method': 'Xyz_Customcheckout/js/action/select-shipping-method'

        }
  }
};

define(
[
    'Magento_Checkout/js/model/quote',
    'Magento_Checkout/js/action/set-shipping-information'
],
function (quote, setShippingAction) {
    "use strict";

    return function (shippingMethod) {
        quote.shippingMethod(shippingMethod);
        // Update totals on summary
        setShippingAction([]);
    };
}
);