Residents pass by a self-service grocery store with no cashier in Guye District of Tangshan, north China's Hebei Province, June 14, 2018. (Xinhua/Yang Shiyao)

A resident scans QR code by a phone to enter a self-service grocery store with no cashier in Guye District of Tangshan, north China's Hebei Province, June 14, 2018. (Xinhua/Yang Shiyao)

A woman pays by her phone at a self-service grocery store with no cashier in Guye District of Tangshan, north China's Hebei Province, June 14, 2018. (Xinhua/Yang Shiyao)