escomplex

Software complexity analysis of JavaScript abstract syntax trees. The back-end for complexity-report.

Installation

The library is published on npm under the name escomplex. To install, you can add it to the dependencies in your package.json file or simply run:

npm i escomplex --save

Usage

You can use escomplex by including it as an Node.js module:

const escomplex = require('escomplex');

The module exports the analyse function.

analyse

The analyse function is used to convert the source code of one or more modules into one or more corresponding report objects containing metrics.

const result = escomplex.analyse(source, options);

Arguments

source

The first argument, source, must be either a string or an array of objects. If it is an array, each object should include a path property that is either a relative or full path to the equivalent module on disk and a code with the contents of the module. As well as identifying each of the result objects, the path property is also used during dependency analysis.

options

The third argument, options, is an optional object containing properties that modify some of the complexity calculations:

• options.logicalor: Boolean indicating whether operator || should be considered a source of cyclomatic complexity, defaults to true.
• options.switchcase: Boolean indicating whether switch statements should be considered a source of cyclomatic complexity, defaults to true.
• options.forin: Boolean indicating whether for...in loops should be considered a source of cyclomatic complexity, defaults to false.
• options.trycatch: Boolean indicating whether catch clauses should be considered a source of cyclomatic complexity, defaults to false.
• options.newmi: Boolean indicating whether the maintainability index should be rebased on a scale from 0 to 100, defaults to false.
• options.skipCalculation: only valid for when source is an array of files Boolean indicating if we should skip processing of certain values, such as the adjacency and visibility matrixes, core sizes, and average values loc, etc.
• options.noCoreSize: Skips creating the visibility matrix and calculating the coreSize, which can be very expensive for large projects

Result Format

The analyze function returns a report of the following format, with some variation depending on the given options.

For a single module

If a single source string is passed in the source argument, the result will be a report object that looks like the following:

{
    maintainability: 171,
    dependencies: [],
    aggregate: {
        sloc: {
            logical: 0,
            physical: 0
        },
        params: 0,
        cyclomatic: 1,
        cyclomaticDensity: 1,
        halstead: {
            vocabulary: 0,
            difficulty: 0,
            volume: 0,
            effort: 0,
            bugs: 0,
            time: 0
        }
    },
    functions: [
        {
            name: '',
            line: 0,
            sloc: {
                logical: 0,
                physical: 0
            },
            params: 0,
            cyclomatic: 1,
            cyclomaticDensity: 1,
            halstead: {
                vocabulary: 0,
                difficulty: 0,
                volume: 0,
                effort: 0,
                bugs: 0,
                time: 0
            }
        },
        ...
    ]
}

The meaning of those values, briefly, is as follows (see metrics for more information on each one):

• report.maintainability: The maintainability index for the module.
• report.dependencies: The array of CommonJS/AMD dependencies for the module.
• report.aggregate.sloc.physical: Physical lines of code for the module. Will be undefined if the syntax tree is not annotated with line number data.
• report.aggregate.sloc.logical: Logical lines of code for the module.
• report.aggregate.params: Parameter count for the module.
• report.aggregate.cyclomatic: Cyclomatic complexity for the module.
• report.aggregate.cyclomaticDensity: Cyclomatic complexity density for the module.
• report.aggregate.halstead.vocabulary: Halstead vocabulary size for the module.
• report.aggregate.halstead.difficulty: Halstead difficulty for the module.
• report.aggregate.halstead.volume: Halstead volume for the module.
• report.aggregate.halstead.effort: Halstead effort for the module.
• report.aggregate.halstead.bugs: Halstead bugs for the module.
• report.aggregate.halstead.time: Halstead time for the module.
• report.functions[n].name: Function name.
• report.functions[n].line: Line number that the function starts on. Will be undefined if the syntax tree is not annotated with line number data.
• report.functions[n].sloc.physical: Physical lines of code for the function. Will be undefined if the syntax tree is not annotated with line number data.
• report.functions[n].sloc.logical: Logical lines of code for the function.
• report.functions[n].params: Parameter count for the function.
• report.functions[n].cyclomatic: Cyclomatic complexity for the function.
• report.functions[n].cyclomaticDensity: Cyclomatic complexity density for the function.
• report.functions[n].halstead.vocabulary: Halstead vocabulary size for the function.
• report.functions[n].halstead.difficulty: Halstead difficulty for the function.
• report.functions[n].halstead.volume: Halstead volume for the function.
• report.functions[n].halstead.effort: Halstead effort for the function.
• report.functions[n].halstead.bugs: Halstead bugs for the function.
• report.functions[n].halstead.time: Halstead time for the function.

For multiple modules

If an array of sources is passed in the source argument, the result will be an object that looks like the following:

{
    reports: [
        ...
    ],
    adjacencyMatrix: [
        [ 0 ]
    ],
    firstOrderDensity: 0,
    visibilityMatrix: [
        [ 0 ]
    ],
    changeCost: 100,
    coreSize: 100,
    loc: 0,
    cyclomatic: 1,
    effort: 0,
    params: 0,
    maintainability: 171
}

Those properties are defined as follows:

• result.reports: An array of report objects, each one in the same format described above but with an extra property path that matches the path property from its corresponding syntax tree. This path property is required because the reports array gets sorted during dependency analysis.
• result.adjacencyMatrix: The adjacency design structure matrix (DSM) for the project. This is a two-dimensional array, each dimension with the same order and length as the reports array. Each row and column represents its equivalent indexed module from the reports array, with values along the horizontal being 1 when that module directly depends on another and values along the vertical being 1 when that module is directly depended on by another. All other values are 0.
• result.firstOrderDensity: The first-order density for the project.
• result.visibilityMatrix: The visibility DSM for the project. Like the adjacency matrix, but expanded to incorporate indirect dependencies. Will be missing if noCoreSize is passed as an option.
• result.changeCost: The change cost for the project. Will be missing if noCoreSize is passed as an option.
• result.coreSize: The core size for the project.
• result.loc: The average per-function count of logical lines of code.
• result.cyclomatic: The average per-function cyclomatic complexity.
• result.effort: The average per-function Halstead effort.
• result.params: The average per-function parameter count.
• result.maintainability: The average per-module maintainability index.

Refer to a more in-depth description of the metrics used for more details.

Related projects

• plato: JavaScript source code visualization, static analysis, and complexity tool.
• jsc: JavaScript source code complexity tool.
• bob: Minimalist-omakase build tool for node.js projects.
• cardio: A web application health tool.
• grunt-complexity: A JavaScript complexity analysis grunt task.
• atom-linter-escomplex: Lining code complexity in Atom editor.
• brackets-crjs: Brackets extension.
• jscomplexity: JS cyclomatic complexity report generator.
• karma-complexity-processor: A preprocessor for karma runner to give some metrics about code complexity.
• crlint: JS linter based on complexity report results.

Contributing

All changes should be submitted in the form of a pull request. Please refer to the contribution guidelines before submitting a pull request.

Source code is in /src. Unit tests are in /test. You can run the tests with npm test. You can run the linter with npm run lint. Make sure you've installed all the dependencies with npm install first.

License

MIT