<span class="discount coupon" data-bind="text: getCouponLabel()"></span>

var config = {
    'config': {
        'mixins': {
            'Magento_SalesRule/js/view/summary/discount': {
                'XXX_YYY/js/view/summary/discount': true

            },
            'Magento_SalesRule/js/view/cart/totals/discount': {
                'XXX_YYY/js/view/cart/totals/discount': true

            },
        }}};

define([
    'Magento_Checkout/js/view/summary/abstract-total',
    'Magento_Checkout/js/model/quote'
], function (Component, quote) {
    'use strict';alert("cart");

    return function (target) {
        return target.extend({
            defaults: {
                template: 'XXX_YY/cart/totals/discount'
            }});
    }
});