inspectpack

library4.7.1jsnpmunverified

Inspectpack is an inspection tool for Webpack frontend JavaScript bundles, providing detailed analysis of module sizes, duplicates, and optimization opportunities. Current stable version is 4.7.1 (released 2024). It is maintained by Formidable Labs and can be used both as a Webpack plugin (DuplicatesPlugin) and as an offline CLI tool. Key differentiators: it is the engine behind webpack-dashboard, offers actionable reports for trimming wasted bytes, and supports both plugin and CLI usage with commands like duplicates, versions, and sizes. It has TypeScript types shipped and requires Node >=6.

devops

npm install inspectpack

github ↗package ↗homepage ↗

INSTALL

IMPORT

SIG · INSPECTPACK

inspectpack

devopsjavascriptv4.7.1

Install

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Import

—

Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

DuplicatesPlugin

✓ const { DuplicatesPlugin } = require('inspectpack/plugin');

✗ const DuplicatesPlugin = require('inspectpack');

DuplicatesPlugin is exported from the subpath 'inspectpack/plugin', not the main export.

inspectpack (CLI)

✓ npx inspectpack --action duplicates --bundle path/to/bundle.js

The CLI is invoked via npx or global install; --action is required.

TypeScript types

✓ import { DuplicatesPlugin } from 'inspectpack/plugin';

✗ import DuplicatesPlugin from 'inspectpack/plugin';

DuplicatesPlugin is a named export, not default.

Shows how to add DuplicatesPlugin to webpack config and run CLI duplicates action.

// webpack.config.js const { DuplicatesPlugin } = require('inspectpack/plugin'); module.exports = { plugins: [ new DuplicatesPlugin({ emitErrors: false, verbose: false, ignoredPackages: [] }) ] }; // CLI usage (after installing): // npx inspectpack --action duplicates --bundle dist/bundle.js

inspectpack --version

Debug

Known issues

breakingVersion 4.x dropped support for Node <6. Ensure your Node version is 6+.

fix

Upgrade Node to v6 or higher.

affects: >=4.0.0

deprecatedThe 'emitHandler' option in DuplicatesPlugin is deprecated. Use 'emitErrors' or custom report handling.

fix

Replace 'emitHandler' with 'emitErrors: true' or implement custom handling.

affects: >=4.0.0

gotchaPlugin only works with webpack 4+; for older webpack, use inspectpack 3.x.

fix

Use inspectpack@3 if you are on webpack 3 or older.

affects: >=4.0.0

gotchaThe CLI expects a single bundle file; it does not handle multiple entry points automatically.

fix

Run inspectpack separately for each bundle or use the plugin.

affects: >=4.0.0

Errors

Common errors & fixes

Error: Cannot find module 'inspectpack/plugin'

Incorrect import path or missing install.

fix

Install inspectpack: npm install --save-dev inspectpack, and use require('inspectpack/plugin')

Invalid configuration object. Plugins have been initialized using an outdated plugin constructor pattern.

Using inspectpack plugin with webpack <4.

fix

Upgrade webpack to 4+ or use inspectpack@3.

TypeError: Cannot read property 'modules' of undefined

Bundle file not found or not a proper webpack bundle.

fix

Ensure the bundle path is correct and the file is a valid webpack output.

The 'emitHandler' option is deprecated; use 'emitErrors' or custom handlers.

Using the deprecated emitHandler option.

fix

Remove emitHandler and set emitErrors: true or implement custom logic.

Upgrade

Version history

4.7.1latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

4 hits · last 30 days

node

Resources

githubhttps://github.com/FormidableLabs/inspectpack ↗

packagehttps://www.npmjs.com/package/inspectpack ↗

homepagehttps://formidable.com/open-source/inspectpack/ ↗