Products Grid

This is an ecommerce site, where you can buy all sorts of ascii faces like (ノ・∀・)ノ and ¯_(ツ)_/¯, in a wide variety of font sizes. The homepage should display a list of products for people to browse.

Please read the instructions and FAQ below before beginning.

Features

products are displayed in a grid.
give the user an option to sort the products in ascending order. Can sort by "size", "price" or "id". The products list should be reloaded when a new sorting option is chosen.
each product has :
- a "size" field, which is the font-size (in pixels). We should display the faces in their correct size, to give customers a realistic impression of what they're buying.
- a "price" field, in cents. This should be formatted as dollars like $3.51.
- a "date" field, which is the date the product was added to the catalog. Dates should be displayed in relative time (eg. "3 days ago") unless they are older than 1 week, in which case the full date should be displayed.
the product grid should automatically load more items as you scroll down.
display an animated "loading..." message while the user waits for the data to load.
to improve the user's experience, we should always pre-emptively fetch the next batch of results in advance, making use of idle-time. But they still should not be displayed until the user has scrolled to the bottom of the product grid.
when the user reaches the end and there are no more products to display, show the message "~ end of catalogue ~".

Ads features

after every 20 products we need to insert an advertisement from one of our sponsors.

Products API

The basic query looks like this: /api/products
The response format is JSON.
To paginate results use the _page parameter, eg: /api/products?_page=10&_limit=15 (returns 15 results starting from the 10th page).
To sort results use the _sort parameter, eg: /api/products?_sort=price. Valid sort values are price, size and id.