When comparing yFiles for HTML vs nnn, the Slant community recommends nnn for most people. In the question“What are the best file managers for UNIX-like systems?” nnn is ranked 1st while yFiles for HTML is ranked 39th.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Great Tooling Support
The huge API can conveniently be explored and programmed against with automatic code completion and intellisense for major Javascript IDEs like WebStorm, Intellij IDEA, Visual Studio Code, and more.
Pro High quality automatic layout support
With the great range of automatic layout options, generating even larger graphs from data sources automatically becomes easy.
Pro Superfast
Pro Rich set of plugins
Pro Extremely lightweight (120 kb)
Pro Unique navigate-as-you-type mode
Pro Awesome new features being added in every release
Pro Minimal configuration with sane defaults
Default options and navigation is simple to grasp.
Pro Has a great wiki
Pro Sessions
Save and resume sessions.
Pro Supports cd-on-quit
Allows for quick switching between nnn and the terminal.
Pro Previews
The file manager has recently added support for preview hovered files using various methods.
Pro Integrates with the desktop environment and opens files in the default applications
Pro Reasonably well-documented
However, it requires some prior knowledge of inner workings of Linux and there are no tutorials (yet). NNN author is making up for this by actively responding to GitHub issues.