Registry / web-framework / vite-legacy-interop

vite-legacy-interop

library1.0.4jsnpmunverified

A Vite 8 plugin that wraps legacy CJS subpath imports in ESM-compatible virtual modules to prevent runtime interop errors. Current version 1.0.4, actively maintained. Designed for Vite 8 and Rolldown, it intercepts imports like `legacy-lib/lib/Button` and replaces them with virtual ESM wrappers that handle CJS-to-ESM interop, solving `SyntaxError` and `ReferenceError` at runtime. Differentiators: targeted at Vite 8 with Rolldown, supports multiple libraries and nested subpaths, minimal configuration, includes debug logging.

web-framework

npm install vite-legacy-interop

github ↗package ↗homepage ↗

INSTALL

IMPORT

SIG · VITE-LEGACY-INTERO

vite-legacy-interop

web-frameworkjavascriptv1.0.4

Install

—

Import

—

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.

legacyInterop

✓ import { legacyInterop } from 'vite-legacy-interop'

✗ import legacyInterop from 'vite-legacy-interop'

Default export is not available; use named import. ESM only.

LegacyInteropOptions

✓ import type { LegacyInteropOptions } from 'vite-legacy-interop'

✗ import { LegacyInteropOptions } from 'vite-legacy-interop'

Only for TypeScript type imports, not a runtime value.

LibConfig

✓ import type { LibConfig } from 'vite-legacy-interop'

✗ import { LibConfig } from 'vite-legacy-interop'

TypeScript only interface, not exported as value.

Configure vite-legacy-interop to wrap CJS subpath imports from 'legacy-lib' in ESM virtual modules.

// vite.config.ts import { defineConfig } from 'vite'; import { legacyInterop } from 'vite-legacy-interop'; export default defineConfig({ plugins: [ legacyInterop({ libs: ['legacy-lib'], showLog: true, apply: 'build', }), ], }); // Now imports like: // import Button from 'legacy-lib/lib/Button' // are transparently wrapped in ESM interop modules.

Debug

Known issues

breakingRequires Vite 8.x; incompatible with Vite 7 or earlier.

fix

Upgrade to Vite 8 or use alternative plugin for earlier Vite versions.

affects: >=1.0.0

gotchaPlugin must be placed before other plugins that transform imports.

fix

Ensure legacyInterop is first in the plugins array.

affects: >=1.0.0

deprecatedOption 'libDir' default is 'lib'; legacy packages with different directory must specify.

fix

Explicitly set 'libDir' if your package uses 'dist' or other paths.

affects: >=1.0.0

gotchaVirtual module IDs start with '\0legacy-interop:' which may conflict with other plugins.

fix

Avoid other plugins using the same namespace prefix.

affects: >=1.0.0

gotchaDoes not handle dynamic imports (import()) or require() calls; only static import statements.

fix

Use static imports for legacy CJS subpaths.

affects: >=1.0.0

Errors

Common errors & fixes

SyntaxError: The requested module 'legacy-lib/lib/Button' does not provide an export named 'default'

Rolldown does not perform CJS-to-ESM interop for subpath imports.

fix

Install and configure vite-legacy-interop with 'legacy-lib' in libs.

ReferenceError: require is not defined

Legacy CJS module is emitted as-is in ESM bundle.

fix

Add vite-legacy-interop plugin with the legacy library name.

Error: The plugin 'vite:legacy-interop' requires Vite >=8.0.0

Attempting to use with older Vite version.

fix

Upgrade Vite to 8.x or remove this plugin.

Upgrade

Version history

1.0.4latest on npm

Audit

Dependencies

viterequiredpeer dependency: requires Vite 8 (^8.0.0) to function

Agent activity

2 hits · last 30 days

node

Resources

githubhttps://github.com/ElJijuna/vite-legacy-interop ↗

packagehttps://www.npmjs.com/package/vite-legacy-interop ↗

homepagehttps://eljijuna.github.io/vite-legacy-interop ↗