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Dual-Runtime Code

Writing code that runs on both Bare and Node.js without conditional requires or runtime detection.

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Package.json Imports Field

The "imports" field in package.json maps module specifiers conditionally by runtime:

{
  "imports": {
    "fs": { "bare": "bare-fs", "default": "fs" },
    "net": { "bare": "bare-net", "default": "net" },
    "path": { "bare": "bare-path", "default": "path" }
  },
  "dependencies": {
    "bare-fs": "^4.7.0",
    "bare-net": "^2.3.1",
    "bare-path": "^3.0.0"
  }
}

Code writes require('fs') — the runtime resolves to the correct module. The "bare" condition matches when running in Bare. The "default" condition is the fallback (Node.js).

Unlike Node.js, the # prefix on import keys is not required in Bare — it is supported for disambiguation but optional.

Source: https://github.com/holepunchto/bare-module

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Third-Party Node.js Packages

Node.js packages use built-in modules internally. On Bare, their dependency tree needs remapping. The bare-node-runtime package provides this:

// Set up Node.js globals (Buffer, process, etc.)
require('bare-node-runtime/global')

// Load Node.js package with full import remapping
const pkg = require('some-node-package', {
  with: { imports: 'bare-node-runtime/imports' }
})

The with: { imports } mechanism applies the complete Node.js-to-Bare module map to the entire dependency tree of the required package. The package and all its dependencies transparently get Bare equivalents instead of Node.js built-ins.

Source: https://github.com/holepunchto/bare-node-runtime

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How It Works Together

For your own code: use "imports" in package.json. Map only the modules you actually use.

For third-party packages: use bare-node-runtime with the with: { imports } mechanism. This handles the full Node.js built-in set.

Example combining both:

{
  "imports": {
    "fs": { "bare": "bare-fs", "default": "fs" },
    "net": { "bare": "bare-net", "default": "net" },
    "path": { "bare": "bare-path", "default": "path" }
  },
  "dependencies": {
    "some-node-package": "^1.0.0",
    "bare-fs": "^4.7.0",
    "bare-net": "^2.3.1",
    "bare-path": "^3.0.0",
    "bare-node-runtime": "^1.2.0"
  }
}

// In your code
if (typeof Bare !== 'undefined') {
  require('bare-node-runtime/global')
}
const avro = require('avsc', typeof Bare !== 'undefined'
  ? { with: { imports: 'bare-node-runtime/imports' } }
  : undefined
)
const fs = require('fs')   // resolved by imports field
const net = require('net')  // resolved by imports field

The runtime detection (typeof Bare !== 'undefined') is only needed at the boundary where third-party packages are loaded. Your own application code stays clean.

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Node.js Compatibility Map

Complete mapping maintained by bare-node-runtime.

Supported

assert, async_hooks, buffer, child_process, console, crypto, dgram, diagnostics_channel, dns, events, fs, http, https, inspector, module, net, os, path, perf_hooks, process, punycode, querystring, readline, repl, stream, string_decoder, timers, tls, tty, url, util, v8, vm, worker_threads, zlib.

Unsupported

cluster, constants, domain, http2, sea, sqlite, sys, test, trace_events, wasi.

Source: https://github.com/holepunchto/bare-node-runtime (imports.json)