copy-asset-in-memory-webpack-plugin

4.0.1 verified Sat Apr 25 auth: no javascript

Webpack 5 plugin to copy processed assets while the compilation is still in memory, before they are written to disk. Version 4.0.1 is the latest stable, with a history of breaking changes aligning with webpack 5. It allows filtering by test/include/exclude, renaming via `to`, transforming content, and optionally deleting original assets. Unlike copy-webpack-plugin which copies from filesystem to output, this plugin copies assets already in webpack's compilation graph. Requires webpack ^5.20.0 and Node >=12.13. Ships TypeScript types.

Common errors

error Cannot find module 'copy-asset-in-memory-webpack-plugin' ↓

cause Package not installed or webpack config not resolving node_modules correctly.

fix

Run npm install -D copy-asset-in-memory-webpack-plugin and ensure your webpack config is in a directory where node_modules can be resolved.

error TypeError: CopyAssetInMemoryPlugin is not a constructor ↓

cause Incorrect import style; likely using ESM default import in a CJS context, or named import where default was expected.

fix

Use const CopyAssetInMemoryPlugin = require('copy-asset-in-memory-webpack-plugin'); in CommonJS, or import CopyAssetInMemoryPlugin from 'copy-asset-in-memory-webpack-plugin'; in ESM (with appropriate configuration).

error Error: Hook is not defined for compilation stage ↓

cause Invalid `stage` value; webpack removed or renamed the stage constant.

fix

Use Compilation.PROCESS_ASSETS_STAGE_SUMMARIZE (default) or another valid stage from webpack's Compilation object.

error Webpack 5 requires node >=10.13.0 but copy-asset-in-memory-webpack-plugin requires >=12.13 ↓

cause Incompatible Node.js version installed (too low).

fix

Upgrade Node.js to version >=12.13.

Warnings

breaking v4.0.0 dropped support for webpack 4. Upgrade to webpack 5 to use this version. ↓

fix Upgrade webpack to ^5.20.0. If stuck on webpack 4, use v3.x.

gotcha Assets cannot be copied outside the output directory. Attempting to do so will silently fail or cause undefined behavior. ↓

fix Ensure the `to` option produces paths relative to the output directory. Do not use absolute paths or '..'.

gotcha deleteOriginalAssets: true deletes the asset's source map as well, because source maps are separate assets that share the same base filename. ↓

fix If you need source maps, either disable deleteOriginalAssets or manually copy the source map before deletion.

deprecated The `stage` option default is Compilation.PROCESS_ASSETS_STAGE_SUMMARIZE. In future webpack versions, this stage might be removed or behave differently. ↓

fix Explicitly set stage to Compilation.PROCESS_ASSETS_STAGE_ADDITIONAL for forward compatibility.

Install

npm install copy-asset-in-memory-webpack-plugin

yarn add copy-asset-in-memory-webpack-plugin

pnpm add copy-asset-in-memory-webpack-plugin

Imports

CopyAssetInMemoryPlugin
wrong
```
import CopyAssetInMemoryPlugin from 'copy-asset-in-memory-webpack-plugin';
```
correct
```
const CopyAssetInMemoryPlugin = require('copy-asset-in-memory-webpack-plugin');
```
This package does not export an ESM default; use CommonJS require in webpack config. For ESM usage, use dynamic import or convert config to .mjs with createRequire.

CopyAssetInMemoryPlugin

wrong

const { CopyAssetInMemoryPlugin } = require('copy-asset-in-memory-webpack-plugin');

correct

import CopyAssetInMemoryPlugin from 'copy-asset-in-memory-webpack-plugin';

TypeScript types are exported as default: `export default class`. Named import fails in CJS because the only export is a default.

type CopyAssetInMemoryPluginOptions

wrong

import { CopyAssetInMemoryPluginOptions } from 'copy-asset-in-memory-webpack-plugin';

correct

import type { CopyAssetInMemoryPluginOptions } from 'copy-asset-in-memory-webpack-plugin';

Options type is a named export in TypeScript. For value imports, use default. Type-only import avoids runtime errors.

Quickstart

Shows CommonJS usage in webpack.config.js, copying .js assets to a 'scripts' subfolder in memory.

// webpack.config.js
const CopyAssetInMemoryPlugin = require('copy-asset-in-memory-webpack-plugin');

module.exports = {
  entry: './src/index.js',
  output: {
    path: path.resolve(__dirname, 'dist'),
    filename: 'bundle.js',
  },
  plugins: [
    new CopyAssetInMemoryPlugin({
      test: /\.js$/,
      to: (fileName) => `scripts/${fileName}`,
    }),
  ],
};