  JavaScript is one of the most popular programming languages on the web.
Despite the language popularity and the increasing size of JavaScript systems,
there is a limited number of visualization tools that can be used by developers
to comprehend, maintain, and evolve JavaScript software. In this paper, we
introduce JSCity, an implementation in JavaScript of the well-known Code City
software visualization metaphor. JSCity relies on JavaScript features and
libraries to show "software cities" in standard web browsers, without requiring
complex installation procedures. We also report our experience on producing
visualizations for 40 popular JavaScript systems using JScity.
