rollup-plugin-json-merge

0.0.2 verified Mon Apr 27 auth: no javascript

A Rollup plugin (v0.0.2, stable but minimal) that merges multiple JSON sources into one output file during bundle build. Supports glob patterns, inline objects, and custom merge functions. Lightweight alternative to manual JSON combination in Rollup pipelines. No major updates since initial release; less feature-rich than @rollup/plugin-json combined with manual merging but simpler for single-file concatenation.

Common errors

error Error: Cannot find module 'glob' ↓

cause Missing glob peer dependency.

fix

npm install glob --save-dev

error TypeError: merge is not a function ↓

cause Using named import incorrectly.

fix

Use default import: import merge from 'rollup-plugin-json-merge'

error Error: Could not resolve 'rollup-plugin-json-merge' ↓

cause Package not installed.

fix

npm install rollup-plugin-json-merge --save-dev

Warnings

gotcha Plugin may not handle conflicting keys across input files; uses shallow assign by default. ↓

fix Provide custom merge function via options.merge to handle conflicts (e.g., deep merge).

gotcha Glob patterns in input must resolve to absolute paths or relative to process.cwd(); no automatic resolution. ↓

fix Use path.resolve or ensure patterns are correct relative to working directory.

gotcha Plugin does not emit warnings for non-existent files; silent failure if no files matched. ↓

fix Validate input files exist before configuring plugin.

Install

npm install rollup-plugin-json-merge

yarn add rollup-plugin-json-merge

pnpm add rollup-plugin-json-merge

Imports

default

wrong

const merge = require('rollup-plugin-json-merge')

correct

import merge from 'rollup-plugin-json-merge'

ESM-only package; use import syntax or dynamic import().

merge

wrong

import { merge } from 'rollup-plugin-json-merge'

correct

import merge from 'rollup-plugin-json-merge'

Package exports a default function only, not a named export.

type Plugin
wrong
```
type Plugin = { ... }
```
correct
```
import type { Plugin } from 'rollup'
```
TypeScript users should import Rollup's Plugin type separately; this package does not export types.

Quickstart

Minimal Rollup config that merges two JSON files into one output using the plugin.

import merge from 'rollup-plugin-json-merge';
export default {
  input: 'src/index.js',
  output: { dir: 'output', format: 'cjs' },
  plugins: [
    merge({
      input: ['src/part1.json', 'src/part2.json'],
      fileName: 'combined.json',
    }),
  ],
};