Registry / devops / rollup-merge-config

rollup-merge-config

library0.0.12jsnpmunverified

Utility to merge multiple Rollup configuration objects with support for custom array and object merging strategies. Current stable version: 0.0.12 (released 2019). Low release cadence (no updates since 2019). Key differentiator: provides array concatenation and object merging specifically tailored for Rollup configs, with optional customizer functions to override default behavior for specific keys. Unlike generic merge libraries (e.g., lodash.merge), it handles Rollup's plugin arrays and nested config structures by default.

devops

npm install rollup-merge-config

github ↗package ↗

INSTALL

IMPORT

SIG · ROLLUP-MERGE-CONFI

rollup-merge-config

devopsjavascriptv0.0.12

Install

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Import

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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 18–223 runs

build_error

glibc

node 18–223 runs

build_error

Code

Verified usage

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

merge

✓ import { merge } from 'rollup-merge-config'

✗ const merge = require('rollup-merge-config')

ESM only; CommonJS require will return the module object, not the merge function directly.

default

✓ import rollupMergeConfig from 'rollup-merge-config'

✗ const { merge } = require('rollup-merge-config')

Default export is an object containing merge and extend. Named exports are preferred.

extend

✓ import { extend } from 'rollup-merge-config'

Identical to merge function; provided for semantic preference.

Shows basic merging of multiple Rollup config objects with default array concatenation and later-key override.

import { merge } from 'rollup-merge-config'; const baseConfig = { input: 'src/index.js', output: { file: 'dist/bundle.js', format: 'cjs' }, plugins: [] }; const clientConfig = { output: { file: 'dist/client.js', format: 'iife' }, plugins: [] }; const serverConfig = { output: { file: 'dist/server.js', format: 'cjs' }, plugins: [] }; // Merge multiple configs; later keys override earlier ones. // Arrays (like plugins) are concatenated. const merged = merge(baseConfig, clientConfig, serverConfig); console.log(merged); // Output: { // input: 'src/index.js', // output: { file: 'dist/server.js', format: 'cjs' }, // plugins: [] // }

Debug

Known issues

gotchaArrays are concatenated by default, not replaced. This may cause duplicate plugins if the same plugin appears in multiple configs.

fix

Use a custom arrayCustomizer to deduplicate, e.g., arrayCustomizer: (a, b, key) => key === 'plugins' ? [...new Set([...a, ...b])] : undefined

affects: >=0.0.0

gotchaProperties with undefined values are not merged and are skipped. If a config explicitly sets a property to undefined, the previous value remains.

fix

Ensure no config sets a property to undefined if you want it removed; use null instead.

affects: >=0.0.0

gotchaDeep nested objects are merged recursively, but only plain objects. Values like instances of classes or functions are replaced, not merged.

fix

If you need to merge non-plain objects, implement a custom objectCustomizer.

affects: >=0.0.0

deprecatedPackage has not been updated since 2019; no TypeScript definitions, no Rollup 3+ support.

fix

Consider using @rollup/pluginutils mergeOptions or manually merging configs.

affects: >=0.0.0

Errors

Common errors & fixes

Uncaught TypeError: merge is not a function

Using default import from CommonJS require where merge is a named export.

fix

Use import { merge } from 'rollup-merge-config' instead of const merge = require('rollup-merge-config').merge

TypeError: config.push is not a function

Misunderstanding that merge can handle arrays of configs like array spread; but merge expects multiple arguments, not an array.

fix

Use merge(config1, config2) or merge(...arrayOfConfigs) with spread, not merge(arrayOfConfigs).

Upgrade

Version history

0.0.12latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

8 hits · last 30 days

node

Resources

githubhttps://github.com/kjoshi1988/rollup-merge-config ↗

packagehttps://www.npmjs.com/package/rollup-merge-config ↗