esbuild-plugin-babel-flow

0.0.5 verified Fri May 01 auth: no javascript

An esbuild plugin for stripping Flow type annotations from JavaScript files using Babel under the hood. Current version is 0.0.5, released as an early-stage package. It integrates into the esbuild plugin system via the 'onLoad' event, transforming code with Babel's transform API to remove Flow types for safe execution. Key differentiators: it bridges esbuild's lack of native Flow support by leveraging Babel's flow-strip-types preset. Alternative plugins exist (e.g., esbuild-plugin-flow), but this one explicitly uses Babel for compatibility. Note that peer dependency esbuild ^0.14.23 is required.

Common errors

error Error: Cannot find module 'esbuild-plugin-babel-flow' ↓

cause Package not installed or not in node_modules.

fix

Run npm install esbuild-plugin-babel-flow --save-dev

error TypeError: esbuild.build is not a function ↓

cause Incorrect esbuild import; common mistake importing default from esbuild.

fix

Use import { build } from 'esbuild'

error ReferenceError: require is not defined in ES module scope ↓

cause Using CommonJS require in an ES module package.json with "type": "module".

fix

Use import { babelFlowPlugin } from 'esbuild-plugin-babel-flow'

Warnings

gotcha Plugin does not perform type checking; it only strips types. Use Flow separately for type validation. ↓

fix Run flow check before or after bundling.

gotcha esbuild peer dependency must be ^0.14.23. Using other versions may cause incompatibility. ↓

fix Ensure esbuild version meets requirement.

gotcha The plugin applies Babel transformation to all loaded JS files, which may slow down builds for large codebases. ↓

fix Use esbuild's filter option to only apply plugin to files containing Flow annotations.

breaking No breaking changes documented as package is very early (v0.0.5). API subject to change. ↓

fix Pin version and monitor releases.

Install

npm install esbuild-plugin-babel-flow

yarn add esbuild-plugin-babel-flow

pnpm add esbuild-plugin-babel-flow

Imports

babelFlowPlugin
wrong
```
import babelFlowPlugin from 'esbuild-plugin-babel-flow'
```
correct
```
import { babelFlowPlugin } from 'esbuild-plugin-babel-flow'
```
The package uses a named export, not a default export. CommonJS require works: const { babelFlowPlugin } = require('esbuild-plugin-babel-flow')

default

wrong

import plugin from 'esbuild-plugin-babel-flow'

correct

There is no default export.

Attempting a default import will result in undefined.

babelFlowPlugin (type)

wrong

import { babelFlowPlugin } from 'esbuild-plugin-babel-flow' (if only type)

correct

import type { babelFlowPlugin } from 'esbuild-plugin-babel-flow'

TypeScript type import is safe; the package does not ship its own types, but you can declare or use Babel types.

Quickstart

Demonstrates setting up esbuild with the Flow-stripping plugin, bundling a file with Flow type annotations.

import { build } from 'esbuild';
import { babelFlowPlugin } from 'esbuild-plugin-babel-flow';

build({
  entryPoints: ['example.flow.js'],
  bundle: true,
  outdir: 'dist',
  plugins: [babelFlowPlugin()],
}).catch(() => process.exit(1));
// Ensure package.json has "type": "module" or use .mjs extension