rollup-plugin-analyzer

Mad metrics for your rollup bundles, know all the things

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rollup-plugin-analyzer

Mad metrics for your rollup bundles, know all the things

npm Travis (.com) Dependents (via libraries.io) npm

TOC

Install

$ npm install --save-dev rollup-plugin-analyzer

Usage

Importing or Requiring

Import as ES Module

import analyze from 'rollup-plugin-analyzer'

Requiring as CJS

const analyze = require('rollup-plugin-analyzer')

Usage from rollup config

export default {
  entry: 'module.js',
  dest: 'index.js',
  format: 'cjs',
  plugins: [analyze()]
}

Usage from build script

rollup({
  entry: 'main.js',
  plugins: [analyze()]
}).then(...)

CI usage example

const limitBytes = 1e6

const onAnalysis = ({ bundleSize }) => {
  if (bundleSize < limitBytes) return
  console.log(`Bundle size exceeds ${limitBytes} bytes: ${bundleSize} bytes`)
  return process.exit(1)
}

rollup({
  entry: 'main.js',
  plugins: [analyze({ onAnalysis, skipFormatted: true })]
}).then(...)

results

logged to console on rollup completion

-----------------------------
Rollup File Analysis
-----------------------------
bundle size:    2.809 KB
original size:  11.436 KB
code reduction: 75.44 %
module count:   5

█████████████████████████████████████████████░░░░░
file:            /virtual-insanity.js
bundle space:    90.64 %
rendered size:   2.546 KB
original size:   2.57 KB
code reduction:  0.93 %
dependents:      1
  - /jamiroquai.js

██░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░
file:            /bundle-a.js
bundle space:    4.27 %
rendered size:   120 Bytes
original size:   309 Bytes
code reduction:  61.17 %
dependents:      0

█░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░
file:            /jamiroquai.js
bundle space:    2.95 %
rendered size:   83 Bytes
original size:   169 Bytes
code reduction:  50.89 %
dependents:      1
  - /the-alphabet-but-incomplete.js
...

results (with summaryOnly enabled)

-----------------------------
Rollup File Analysis
-----------------------------
bundle size:    2.809 KB
original size:  11.436 KB
code reduction: 75.44 %
module count:   5

/virtual-insanity.js
█████████████████████████████████████████████░░░░░ 90.64 % (2.546 KB)
/bundle-a.js
██░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ 4.27 % (120 Bytes)
/jamiroquai.js
█░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ 2.95 % (83 Bytes)
/the-alphabet-but-incomplete.js
░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ 1.17 % (33 Bytes)
/the-declaration-of-independence.js
░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ 0.96 % (27 Bytes)

Options

FAQ

Why is the reported size not the same as the file on disk?

This module is geared towards the details of the individual modules that make up the bundle and their relative impact to bundle size. That’s a detailed way of saying, it doesn’t really care about size on disk. There are other options which focus on size on disk as well as delivery size which can be used alongside this module (or in place of if your concern is not per module impact). In particular rollup-plugin-size-snapshot seems like a great option for that.

Getting a bit further into the details, rather than just intent, of why the reported size differs from that on disk. We get the module data from Rollup which reports it after chunk (module) resolution and tree-shaking, but before post-processing (such as minification and compression). We then add the sizes of each of those modules together, this is the bundle size that we report.

That means it won’t account for post-processing from other plugins and also won’t account for post-processing by Rollup itself, which includes boilerplate / shims depending on what the output format is (CJS, ESM, iife, etc…).

Why am I seeing multiple analysis outputs emitted?

Rollup allows you to output to multiple files. If you are outputting to multiple files you will get a distinct analysis for each output file. Each analysis will contain data on the files imported by the respective target.

One way to manipulate the number of reports in this scenario is through the onAnalysis callback option:

// Track iterations over output files
let analyzePluginIterations = 0;

export default {
  input: 'myIsomorphicModule.js',
  output: [
    {
      name: 'myIsomorphicModule',
      format: 'cjs',
      entryFileNames: '[name].cjs'
    },
    {
      name: 'myIsomorphicModule',
      format: 'es',
      entryFileNames: '[name].mjs'
    }
  ],
  plugins: [
    analyze({
      onAnalysis: () => {
        if (analyzePluginIterations > 0) {
          throw ''; // We only want reports on the first output
        }
        analyzePluginIterations++;
      }
    })
  ]
}

License

MIT © Andrew Carpenter