Expand Rollup Build Options by File Glob Patterns

Helps maintaining many Rollup build targets by using file glob patterns. Reduces copying & pasting of options in the Rollup configuration.

Synopsis

Let us assume the following project structure with two components and their tests:

src/
├── first
│   ├── first.md
│   ├── first.ts
│   └── first.test.ts
└── second
    ├── second.md
    ├── second.ts
    └── second.test.ts

Rollup configuration usually contains options for building each component and each test:

export default [
  {
    input: 'src/first/first.ts',
    output: { file: 'dist/first.js' }
  },
  {
    input: 'src/second/second.ts',
    output: { file: 'dist/second.js' }
  }
  {
    input: 'src/first/first.test.ts',
    output: { file: 'src/first/first.test.js' }
  },
  {
    input: 'src/second/second.test.js',
    output: { file: 'src/second/second.test.js' }
  }
]

The copies of options for building components and their tests can be avoided by specifying each build target only once using file patterns with name placeholders delimited by square brackets:

import globOpts from 'rollup-glob-opts'

export default async () => [
  ...await globOpts({
    input: 'src/[name]/[name].ts',
    output: { file: 'dist/[name].js' }
  }),
  ...await globOpts({
    input: 'src/[name]/[name].test.ts',
    output: { file: 'src/[name]/[name].test.js' }
  })
]

The name placeholders in the input property are replaced with * and looked for in the local file system. One build options object is created for each pattern match.

The output property can point either to an object or to an array of objects, if multiple bundles are generated from one input.

Installation

You can install this package using your favourite Node.js package manager:

npm i -D rollup-glob-opts
yarn add -D rollup-glob-opts
pnpm i -D rollup-glob-opts

Debugging

If you need to investigate an unexpected behaviour of the file globbing, you can use the process environment, for example:

DEBUG=glob-opts rollup -c
...
  glob-opts expanding "src/[name]/[name].ts" +0ms
  glob-opts 4 files found for "src/*/*.ts". +1ms
  glob-opts matching "src/first/first.test.ts" with /^src\/([^/]+)\/([^/]+)\.ts$/ +0ms
  glob-opts dropping "src/first/first.test.ts", inconsistent "[name]": "first" != "first.test" +0ms
  glob-opts matching "src/first/first.ts" with /^src\/([^/]+)\/([^/]+)\.ts$/ +0ms
  glob-opts matching "src/second/second.test.ts" with /^src\/([^/]+)\/([^/]+)\.ts$/ +1ms
  glob-opts dropping "src/second/second.test.ts", inconsistent "[name]": "second" != "second.test" +0ms
  glob-opts matching "src/second/second.ts" with /^src\/([^/]+)\/([^/]+)\.ts$/ +0ms
  glob-opts 2 files matched "src/[name]/[name].ts". +0ms
  glob-opts matching "src/first/first.ts" with /^src\/([^/]+)\/([^/]+)\.ts$/ +0ms
  glob-opts new output "dist/first.js" for "dist/[name].js" +0ms
  glob-opts matching "src/second/second.ts" with /^src\/([^/]+)\/([^/]+)\.ts$/ +0ms
  glob-opts new output "dist/second.js" for "dist/[name].js" +0ms
...

Contributing

In lieu of a formal styleguide, take care to maintain the existing coding style. Lint and test your code using npm test.

License

Copyright (c) 2021-2024 Ferdinand Prantl

Licensed under the MIT license.