eslintcc

ESLint Complexity of Code

ESLintCC is a ECMAScript/JavaScript tool that computes complexity of code by using ESLint

ESLint calculates complexity of code, while this tool only collects a report based on his complexity rule messages

Installation and Usage

Requirements, principles of local and global installation and usage are the same as ESLint Installation and Usage

Globally:

$ npm install -g eslintcc
$ eslintcc yourfile.js

Locally:

$ npm install eslintcc
$ ./node_modules/.bin/eslintcc yourfile.js

Integration in JavaScript application:

const { Complexity } = require('eslintcc');

const complexity = new Complexity();
const report = complexity.executeOnFiles(['yourfile.js']);

console.log(JSON.stringify(report, null, '\t'));

Note: ESLintCC ignores all plugins and rules, specified in configuration files, and uses to generate a report only complexity rules. So there is no need to install plugins dependencies for use ESLintCC. But, if using a shareable configuration package, you use must also be installed locally or globally to work with a locally or globally installed ESLintCC.

Configuration

ESLintCC uses ESLint along with Its configuration system. You can use configuration comments and files, as described in the configuration for ESLint.

Difference: ESLintCC uses its own settings for complexity rules, so they cannot be overridden through a configuration file. However, you can disable them locally in the file.

Features:

1. You can configurate parserOptions and parser for specify the JavaScript language support. .eslintrc.json:

{
  "parserOptions": {
    "ecmaVersion": 2017
  }
}

1. You can disable checks for a specific complexity rule for a file or part of file using a comment:

// For a file
/* eslint max-params: off, max-depth: off */

function myFunc(a, b, c, d, e) {
  //...
}

// For a block
/* eslint-disable max-params */
function myFunc(a, b, c, d, e) {
  //...
}
/* eslint-enable max-params */
function myFunc2(a, b) {
  //...
}

// For a line
/* eslint-disable-next-line max-params */
function myFunc(a, b, c, d, e) {
  //...
}

Complexity ranks

Every function and block will be ranked from A (best complexity score) to F (worst one). This ranks is based on the ranks of complexity of the Python Radon.

Rank Risk

• A low - simple block
• B low - well structured and stable block
• C moderate - slightly complex block
• D more than moderate - more complex block
• E high - complex block, alarming
• F very high - error-prone, unstable block

Ranks corresponds to rule complexity scores as follows:

Rules	A	B	C	D	E	F
Logic:
complexity	1 - 5	6 - 10	11 - 20	21 - 30	31 - 40	41 +
max-depth	1 - 2	3	4 - 5	6 - 7	8	9 +
max-nested-callbacks	1 - 3	4 - 5	6 - 10	11 - 15	16 - 20	21 +
max-params	1	2	3 - 4	5	6	7 +
Raw:
max-lines	1 - 75	76 - 150	151 - 300	301 - 450	451 - 600	601 +
max-lines-per-function	1 - 13	14 - 25	26 - 50	51 - 75	76 - 100	101 +
max-statements	1 - 3	4 - 5	6 - 10	11 - 15	16 - 20	21 +

Note: For rank "C", the maximum score, using from the standard score of ESLint rules. See complexity rules. Other rules are calculated relative to the values of the "complexity" rule.

Example formula: [5, 10, 20, 30, 40].map(score => Math.round((score / 20) * defaultRuleScoreLimit))

Command line options

Command line format:

$ eslintcc [options] file.js [file.js] [dir]

Option	Type	Description
--rules <rules>, -r=<rules>	Array of String	Rule, or group: all, logic, raw. Default: logic
--format <format>, -f=<format>	String	Use a specific output format, text or json. Default: text
--average, -a	Flag	Show the average complexity at the end of output, if used text format
--show-rules, -sr	Flag	Show rule name and value, if used text format
--greater-than <value>, -gt=<value>	String or Number	Will show rules more than rank a, b, c, d, e, or rank value
--less-than <value>, -lt=<value>	String or Number	Will show rules less than rank b, c, d, e, f, or rank value
--no-inline-config, -nlc	Flag	Disable the use of configuration comments (such as /*eslint-disable*/)
--max-rank <value>, -mr=<value>	String or Number	Maximum allowed complexity rank for a single message. Default: C
--max-average-rank <value>, -mar=<value>	String or Number	Maximum allowed complexity rank for average value. Default: B

If the rank value for one message or the average value is higher than the allowed value, the program terminates with error code 1

Command examples

Output as JSON and show rules more than rank E:

$ eslintcc -f=json -gt=e file.js

Use only 2 rules and show rule name:

$ eslintcc --rules complexity --rules max-depth --show-rules file.js