Next Bundle Analyzer

Motivation

Webpack Bundle Analyzer is a great tool to analyze the bundles of web applications built on top of Webpack but trying to use it to optimize a large website with many pages can be tricky because you don't know which pages the different chunks belong to.

There is an official wrapper dedicated to Next.js, @next/bundle-analyzer, but it only allows (for now) to generate standard reports for the server and client builds of Next.

This library generates customized Webpack Bundle Analyzer reports in order to make them easier to use for Next users.

Installation

We recommend installing next-bundle-analyzer as dev dependency:

1npm install -D next-bundle-analyzer

or

1yarn add -D next-bundle-analyzer

Usage

1// next.config.js
2
3const shouldAnalyzeBundles = process.env.ANALYZE === true;
4
5let nextConfig = {
6  // [...]
7};
8
9if (shouldAnalyzeBundles) {
10  const withNextBundleAnalyzer =
11    require('next-bundle-analyzer')(/* options come there */);
12  nextConfig = withNextBundleAnalyzer(nextConfig);
13}
14
15module.exports = nextConfig;

⚠️ If next-bundle-analyzer has been installed as dev dependency, itshould be required conditionally to prevent breaking Next.js in production.

Options

Root options

Option	Values	Default	Description
clientOnly	true false	true	When true, generate only a report for client side build.
enabled	true false	true	Allows to enable/disable the plugin.
format	'html' 'json' ['html', 'json']	'html'	The format of the report(s) to generate. It can be a single format or a list.
html	See HTML options.	{}	Options related to the HTML report.
json	See JSON options.	{}	Options related to the JSON report.
reportDir	string	'analyze'	Name of the directory that will contain the reports. Relative to Webpack output path.
reportFilename	string	'bundles' '-client' and '-server' suffixes will be added if clientOnly is false.	Name of the report without the extension.

HTML options

Option	Values	Default	Description
open	true false	true	When true, report opens automatically once generated.

JSON options

Option	Values	Default	Description
filter	Object with the same structure than the JSON report to filter. Use true as value to keep a key.	null	Filter to apply to the JSON report in order to keep only some keys.