circular-dependency-plugin

What is circular-dependency-plugin?

The circular-dependency-plugin is an npm package used to detect circular dependencies in JavaScript projects. It is particularly useful in large codebases where circular dependencies can lead to difficult-to-debug issues and performance problems.

What are circular-dependency-plugin's main functionalities?

Basic Usage

This code demonstrates the basic usage of the circular-dependency-plugin in a webpack configuration. It shows how to exclude certain files, include specific directories, fail on error, and set the current working directory.

const CircularDependencyPlugin = require('circular-dependency-plugin');

module.exports = {
  // other webpack config
  plugins: [
    new CircularDependencyPlugin({
      // exclude detection of files based on a RegExp
      exclude: /a\.js|node_modules/,
      // include specific files based on a RegExp
      include: /dir/,
      // add errors to webpack instead of warnings
      failOnError: true,
      // allow import cycles that include an asyncronous import,
      allowAsyncCycles: false,
      // set the current working directory for displaying module paths
      cwd: process.cwd(),
    })
  ]
};

Custom Error Message

This code sample shows how to customize the error message when a circular dependency is detected. The onDetected callback allows you to push a custom error message to the compilation errors.

const CircularDependencyPlugin = require('circular-dependency-plugin');

module.exports = {
  // other webpack config
  plugins: [
    new CircularDependencyPlugin({
      onDetected({ module: webpackModuleRecord, paths, compilation }) {
        compilation.errors.push(new Error(paths.join(' -> ')));
      }
    })
  ]
};

Other packages similar to circular-dependency-plugin

madge

Madge is a JavaScript library that can analyze the dependency graph of your project and detect circular dependencies. Unlike circular-dependency-plugin, which is a webpack plugin, Madge can be used as a standalone tool or integrated into various build processes.

dependency-cruiser

Dependency-cruiser is a tool to analyze and visualize dependencies in JavaScript and TypeScript projects. It can detect circular dependencies and offers more extensive analysis options compared to circular-dependency-plugin. It can be used as a CLI tool or integrated into build processes.

README

Circular Dependency Plugin

Detect modules with circular dependencies when bundling with webpack.

Circular dependencies are often a necessity in complex software, the presence of a circular dependency doesn't always imply a bug, but in the case where you believe a bug exists, this module may help find it.

Webpack Versions

The latest major version of this plugin 5, supports webpack 4.x.x as a peer dependency. Major version 4 of this plugin and below are intended to support webpack 3.x.x and below as a peer dependency.

Basic Usage

// webpack.config.js
const CircularDependencyPlugin = require('circular-dependency-plugin')

module.exports = {
  entry: "./src/index",
  plugins: [
    new CircularDependencyPlugin({
      // exclude detection of files based on a RegExp
      exclude: /a\.js|node_modules/,
      // add errors to webpack instead of warnings
      failOnError: true,
      // set the current working directory for displaying module paths
      cwd: process.cwd(),
    })
  ]
}

Advanced Usage

// webpack.config.js
const CircularDependencyPlugin = require('circular-dependency-plugin')

module.exports = {
  entry: "./src/index",
  plugins: [
    new CircularDependencyPlugin({
      // `onStart` is called before the cycle detection starts
      onStart({ compilation }) {
        console.log('start detecting webpack modules cycles');
      },
      // `onDetected` is called for each module that is cyclical
      onDetected({ module: webpackModuleRecord, paths, compilation }) {
        // `paths` will be an Array of the relative module paths that make up the cycle
        // `module` will be the module record generated by webpack that caused the cycle
        compilation.errors.push(new Error(paths.join(' -> ')))
      },
      // `onEnd` is called before the cycle detection ends
      onEnd({ compilation }) {
        console.log('end detecting webpack modules cycles');
      },
    })
  ]
}

If you have some number of cycles and want to fail if any new ones are introduced, you can use the life cycle methods to count and fail when the count is exceeded. (Note if you care about detecting a cycle being replaced by another, this won't catch that.)

// webpack.config.js
const CircularDependencyPlugin = require('circular-dependency-plugin')

const MAX_CYCLES = 5;
let numCyclesDetected = 0;

module.exports = {
  entry: "./src/index",
  plugins: [
    new CircularDependencyPlugin({
      onStart({ compilation }) {
        numCyclesDetected = 0;
      },
      onDetected({ module: webpackModuleRecord, paths, compilation }) {
        numCyclesDetected++;
        compilation.warnings.push(new Error(paths.join(' -> ')))
      },
      onEnd({ compilation }) {
        if (numCyclesDetected > MAX_CYCLES) {
          compilation.errors.push(new Error(
            `Detected ${numCyclesDetected} cycles which exceeds configured limit of ${MAX_CYCLES}`
          ));
        }
      },
    })
  ]
}

Changelog

5.0.0

• Support for webpack 4
• Exclude logic will now be checked regardless of presence of onDetected method