@gathertown/circular-dependency-plugin

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.

Differences from the upstream repo

Adds support for a faster development workflow by providing options to reduce the number of times this plugin does its processing.

// webpack.config.js
module.exports = {
  ...
  plugins: [
    new CircularDependencyPlugin({
      // enable developer mode
      devMode: true,
      // check only once every 2 minutes
      checkInterval: 2 * 60 * 1000,
      // Other configuration options
      ...
    })
  ]
  ...
}

Webpack Versions

The latest major version of this plugin 5

Basic Usage

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

module.exports = {
  entry: "./src/index",
  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,
      // e.g. via import(/* webpackMode: "weak" */ './file.js')
      allowAsyncCycles: false,
      // 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}`
          ));
        }
      },
    })
  ]
}

Maintenance

This module is maintained despite few changes being necessary, please open issues if you find any bugs relating to integration with webpack core.