Bublé

0.20.0 verified Fri May 01 auth: no javascript maintenance

Bublé is a fast ES2015+ to ES5 compiler that requires zero configuration. Version 0.20.0 is current but in maintenance mode. It was designed before modern browsers supported ES2015, and now only recommended for IE11 compatibility. Unlike Babel, Bublé does not require plugins or presets, making it simpler but less extensible. It supports ES2015 features like arrow functions, template literals, destructuring, and let/const, plus some ES2016/ES2017 features (exponentiation, async/await). No new features will be added; only bugfixes.

Common errors

error Error: Cannot find module 'acorn' ↓

cause Missing acorn dependency (Bublé uses it internally).

fix

Run npm install buble which includes acorn as a dependency.

error TypeError: buble.transform is not a function ↓

cause Invalid import: trying to use ES import syntax on CJS module.

fix

Use const buble = require('buble'); instead of import buble from 'buble';.

error SyntaxError: Unexpected token (1:6): import statement ↓

cause Bublé does not support transforming import/export statements by default.

fix

Add option transforms: { modules: false } or use Babel for ES modules.

Warnings

deprecated Bublé is in maintenance mode; no new features will be added. ↓

fix Consider Babel or SWC for modern needs unless IE11 support is required.

breaking In v0.17+, the 'acorn' dependency changed; custom acorn plugins may break. ↓

fix Update userland plugins to be compatible with acorn 5+.

gotcha Bublé does not support dynamic import() or optional chaining. ↓

fix Use Babel or TypeScript for those features.

gotcha Source maps require magic-string; ensure it is installed. ↓

fix npm install magic-string@^0.25.0 as a dependency.

Install

npm install buble

yarn add buble

pnpm add buble

Imports

default (transform)
wrong
```
import buble from 'buble';
```
correct
```
const buble = require('buble'); buble.transform(source);
```
Bublé does not ship ES module; use CommonJS require() for Node compatibility.
transform
wrong
```
import { transform } from 'buble';
```
correct
```
const { transform } = require('buble');
```
Named import from CJS is fine, but ESM import fails due to missing .mjs entry.

buble (CLI)

wrong

import buble from 'buble';

correct

const exec = require('child_process').execSync('buble input.js');

CLI tool is separate from npm package; install globally with -g.

Quickstart

Shows basic usage of Bublé's transform function: compile arrow function to ES5, disable module transformation.

const buble = require('buble');
const result = buble.transform('const x = () => 1;', {
  transforms: { modules: false },
  source: 'input.js'
});
console.log(result.code); // 'var x = function () { return 1; };'