Generally, invoices can be issued for things purchased in major online supermarkets and online shopping malls (such as JD.COM, Taobao and other online merchants), such as health care products, nutritional products, fruits and flowers.
However, things purchased from offline vendors or small shops are often not invoiced, because most of these businesses are not filed with the tax bureau. If you want to issue an invoice, it is recommended to buy it through formal channels.