But all around China, gloom and uncertainty are the word.

Economic growth is slowing, and the country’s hundreds of millions of middle-class shoppers seem to be holding on more tightly to their pocketbooks. Tech companies are antsy about the government’s more interventionist attitude toward big business. The tariff fight with the United States is casting a pall not simply over trade, but over China’s future writ large. This month, Alibaba cut its sales forecast for the year ending in March by around 5 percent, citing the wobbly economy and the trade war.

Meanwhile, some young Chinese shoppers seem less enthused this year about celebrating manic consumerism.

Yang Sun, a 26-year-old from the northern city of Xi’an, said that the Singles Day discounts were no longer good enough to persuade her to wait all year to buy the things she wanted. Wang Xin, 24, an engineer in Shanghai, said he had rediscovered the joys of shopping offline.

“Singles Day just doesn’t hold that much appeal for me,” Mr. Wang said.

Asked about the current mood among Chinese consumers, Joseph C. Tsai, Alibaba’s executive vice chairman, told reporters on Sunday that Alibaba should be understood in the context of the epochal rise of China’s middle class.

“That trend is not going to stop, trade war or no trade war,” he said. “Any kind of short-term economic effects, we believe, will be cyclical.”