代码：

define(
    [
        'jquery',
        'mage/storage',
        'Magento_Checkout/js/model/quote',
        'Magento_Catalog/js/price-utils',
        'Magento_Checkout/js/view/summary/abstract-total',
        'Magento_Checkout/js/model/url-builder'
    ],
    function ($, storage, quote, priceUtils, Component, urlBuilder) {
        "use strict";
        let isVisible = false;
        let discount = 0;
        // 获取Quote的优惠
        storage.get(
            urlBuilder.createUrl('/aiweline/quote/upsell')
        ).done(function (response) {
            if (response.upsell_discount_amount) {
                isVisible = true;
                discount = upsell_discount_amount;
            }
        }).error(function (response) {
            errorProcessor.process(response);
        }).always(function () {
        });
        return Component.extend({
            defaults: {
                template: 'Aiweline_Upsell/checkout/summary/upsell-discount'
            },
            isDisplayedCustomdiscount: function () {
                return isVisible;
            },
            getCustomDiscount: function () {
                return priceUtils.formatPrice(discount, quote.getPriceFormat());
            }
        });
    }
);

重点：

return priceUtils.formatPrice(discount, quote.getPriceFormat());