Here are some examples to help you grasp the concept of Drawer.
All the listed drawers are provided with the VisualN Basic Drawers submodule from the VisualN package.
Can be tested locally on your site when enabled, at "VisualN > Available Drawer Preview" page.

You may also want to visit the main page of the VisualN Project (https://visualn.org/).
 

Openstreetmap based leaflet map with geotags support

Basic linechart with variable number of series

The drawer uses c3.js library for creating simple charts. Multiple data series can be configured each with its label.

List of news feed items with image, link title and short text on each line

The resultant markup is created on server side without involving any js. Serves as a basic examples of items lists usually created by views module.

Slick.js based slideshow gallery of images or HTML markup with basic (optional) controls

The drawer uses slick.js library to create slider galleries.

Table with variable number of rows and columns

The resultant markup is created on server side without involving any js.
The drawer demonstrates resource-type agnostic feature of drawers - no matter what type of resource is provided, it can be used by any drawer.

Also it can be used to check data structure used by other drawers - just choose an appropriate data generator plugin used by target drawer.