jstransformer-babel

2.1.0 verified Sat Apr 25 auth: no javascript maintenance

A JSTransformer plugin that wraps Babel for transpiling JavaScript. Current version 2.1.0 supports Babel 6 and is in maintenance mode. The package provides a unified interface through the JSTransformer architecture, enabling render, renderFile, and renderString APIs. Unlike direct Babel usage, it filters unsupported options and supports .babelrc configuration when a filename is provided. Key differentiator: it integrates with the JSTransformer ecosystem (used by Pug, etc.) but does not include presets by default, requiring explicit presets like 'es2015' in Babel 6.

Common errors

error Error: Requires Babel "$BABEL_VERSION", but is loaded with "6.26.3". If you are sure you have a compatible version of Babel, it is likely that you are pulling in different versions of Babel. Try uninstalling all Babel packages and reinstalling them. ↓

cause Incompatible Babel version or multiple Babel installations.

fix

Install compatible Babel version: npm install @babel/core@^7.0.0 (if jstransformer-babel supports Babel 7) or stick to Babel 6.

error Error: Couldn't find preset "env" relative to directory ↓

cause Preset 'env' is not installed.

fix

npm install @babel/preset-env --save-dev

error TypeError: babel.render is not a function ↓

cause Directly requiring jstransformer-babel without wrapping with jstransformer.

fix

Use: const jstransformer = require('jstransformer'); const babel = jstransformer(require('jstransformer-babel'));

Warnings

breaking jstransformer-babel v2 requires explicit presets; no longer defaults to ES2015. ↓

fix Pass an array of presets (e.g., ['env']) or configure .babelrc.

deprecated jstransformer v1 is being replaced by jstransformer v2 which uses a different API. ↓

fix Migrate to jstransformer v2 with updated interface.

gotcha The package only implements 'render'; other methods (renderString, renderFile) are derived but may have edge cases. ↓

fix Test derived methods thoroughly with your Babel options.

gotcha Babel configuration files (.babelrc) only apply when filename is passed to renderFile or renderFileAsync. ↓

fix Use renderFile* or pass { filename: 'example.js' } to render.

Install

npm install jstransformer-babel

yarn add jstransformer-babel

pnpm add jstransformer-babel

Imports

jstransformer-babel

wrong

const babel = require('jstransformer-babel')

correct

const babel = require('jstransformer')(require('jstransformer-babel'))

Must wrap with jstransformer to access render* methods.

render
wrong
```
babel.render(src, { presets: ['es2015'] })
```
correct
```
babel.render(src, { presets: ['env'] })
```
From v2, presets are not default; 'es2015' is outdated; use '@babel/preset-env'.

renderFile

wrong

babel.renderFile('input.js', {}, function(err, result) {})

correct

babel.renderFile('input.js', function(err, result) {})

renderFile accepts options as second argument and callback as third.

Quickstart

Transpile modern JS to compatible code using Babel 6 via jstransformer-babel with preset-env.

const jstransformer = require('jstransformer');
const babel = jstransformer(require('jstransformer-babel'));
const src = `const x = () => 1`;
const result = babel.render(src, {
  presets: [['@babel/preset-env', { targets: { node: 'current' } }]]
});
console.log(result.body);