Scrape Taobao / Tmall keyword or category listings

Returns the products Taobao lists for a keyword q (or a category) as JSON: products (position, itemId, title, url, image, price in yuan with currency CNY, priceLabel (Taobao’s price tag, e.g. 优惠价), localPrices (the same price in the storefront’s currency, HKD and TWD), shopId, shopName, descriptionMatchScore, freeShipping, categoryId, rootCategoryId, sellingPoints, reviewHighlights), totalResults (how many listings Taobao reports), and filterOptions (brand and property facets; pass an option’s filter value back as filter). Sort by relevance, sales or price and filter by a yuan price range (products whose listed price falls outside it are left out and counted in droppedOutsidePriceRange). Taobao shows signed-out visitors only the first 20 products of a list, so one call returns up to 20 (narrow with price ranges and filters to reach more). When Taobao has no list for the keyword, the call answers with the list of the closest keyword Taobao itself suggests and says so: keywordSubstituted true and matchedKeyword. Text comes in Chinese as sellers write it. Companion to /marketplace/taobao-product. One unit per call.