nocuous

A static code analysis tool for JavaScript and TypeScript.

Installing the CLI

If you want to install the CLI, you would need to have Deno installed first and then on the command line, you would want to run the following command:

$ deno install --name nocuous --allow-read --allow-net --allow-hrtime --import-map https://deno.land/x/nocuous/import_map.json -f https://deno.land/x/nocuous/cli.ts

You can also "pin" to a specific version by using nocuous@{version} instead, for example https://deno.land/nocuous@1.0.0/import_map.json and https://deno.land/nocuous@1.0.0/cli.ts.

The CLI comes with integrated help which can be accessed via the --help flag.

Using the API

If you want to incorporate the API into an application, you need to import it into your code. For example the following will analyze the Deno std assertion library and its dependencies resolving with a map of statistics:

import { instantiate, stats } from "https://deno.land/x/nocuous/mod.ts";

await instantiate();

const results = await stats(
  new URL("https://deno.land/std/testing/asserts.ts"),
);

console.log(results);

It is recommended though that you "pin" to a specific version of the library, for example to import from version 1.0.0 you would want to import from https://deno.land/x/nocuous@1.0.0/mod.ts.

Architecture

The tool uses swc as a Rust library to parse code and then run analysis over the parsed code. It is then compiled to Web Assembly and exposed as an all-in-one API. Code is loaded via the JavaScript runtime and a resolver can be provided to allow for custom resolution logic.

Background

The statistics collected around code toxicity are based directly on Erik Dörnenburg's article How toxic is your code?.

The default metrics are based on what is suggested in the article. When applying to TypeScript/JavaScript there are some adaptation that is required:

Metric	Table Label	Description	Default Threshold
File length	L	The number of lines in a file.	500
Class data abstraction coupling	CDAC	The number of instances of other classes that are "new"ed in a given class.	10
Anon Inner Length	AIL	Class expressions of arrow functions length in number of lines.	35
Function Length	FL	The number of statements in a function declaration, function expression, or method declaration.	30
Parameter Number	P	The number of parameters for a function or method	6
Cyclomatic Complexity	CC	The cyclomatic complexity for a function or method	10
Binary Expression Complexity	BEC	How complex a binary expression is (e.g. how many && and `
Missing Switch Default	MSD	Any switch statements that are missing the default case.	1