buble

What is buble?

Bublé is a JavaScript compiler that takes your ES2015+ code and turns it into code that can run in older browsers. It is designed to be fast and to produce compact output.

What are buble's main functionalities?

Transpiling ES6 to ES5

Bublé can transpile modern ES6+ syntax to ES5, making it compatible with older browsers. This example shows how an arrow function is transformed into a regular function.

const buble = require('buble');
const result = buble.transform(`const add = (a, b) => a + b;`);
console.log(result.code); // 'var add = function (a, b) { return a + b; };'

Source Maps

Bublé can generate source maps, which are useful for debugging. This example shows how to generate a source map for the transformed code.

const buble = require('buble');
const result = buble.transform(`const add = (a, b) => a + b;`, { source: 'input.js', file: 'output.js' });
console.log(result.map);

Custom Transforms

Bublé allows you to customize which transformations to apply. This example shows how to disable the transformation of ES6 classes.

const buble = require('buble');
const result = buble.transform(`class Person { constructor(name) { this.name = name; } }`, { transforms: { classes: false } });
console.log(result.code);

Other packages similar to buble

babel

Babel is a widely-used JavaScript compiler that supports a wide range of plugins and presets for transforming ES6+ code to ES5. It is more feature-rich and extensible compared to Bublé, but it can be slower and produce larger output.

typescript

TypeScript is a superset of JavaScript that adds static types. It also includes a compiler that can transpile TypeScript (and modern JavaScript) to ES5. While it offers more features like type checking, it is more complex to set up and use compared to Bublé.

esbuild

esbuild is an extremely fast JavaScript bundler and minifier. It can also transpile modern JavaScript to older versions. It is known for its speed and efficiency, but it is less configurable than Babel.

README

Bublé

The blazing fast, batteries-included ES2015 compiler. Try it out at buble.surge.sh

Is this a Babel rip-off?

Yes – insofar as it's a tool that can transform ES2015 into JavaScript that will run today. The key differences:

• Bublé limits itself to ES2015 that can be transpiled to compact, performant ES5
• There are no plugins or presets – less extensibility, but also zero configuration
• It's comparatively tiny and many times faster

Unlike Babel, 100% spec compliance isn't an over-riding goal – for example it won't add runtime checks to ensure that you're not instantiating classes without new. (Complete spec compliance is impossible anyway, as some ES2015 features can't be transpiled.) You'll also need to bring your own polyfill (e.g. es6-shim). You have been warned!

How do I use it?

Via the command line...

npm install -g buble
buble input.js > output.js

...or via the JavaScript API:

var buble = require( 'buble' );
var result = buble.transform( source ); // { code: ..., map: ... }

What's supported?

Currently:

• Arrow functions
• Classes (with caveats – see below)
• Object shorthand methods and properties
• Template strings (untagged only – see below)
• Object and array destructuring
• Default parameters
• Block scoping (let and const)
• Binary and octal literals

What's not supported?

Bublé only transpiles language features – it doesn't attempt to shim or polyfill the environment. If you want to use things like array.findIndex(...) or 'x'.repeat(3) you'll have to bring your own polyfill.

It also refuses to transpile things that result in ES5 code with size or performance hazards (subject to change! It might support some of these features in future), or which are altogether impossible to transpile to ES5.

• Computed properties of objects and classes
• Tagged template strings
• Iterators
• Generators
• Regex unicode flag
• Modules (pssst... use Rollup!)
• Map, Set, WeakMap, WeakSet, Proxy, Symbol
• Tail call optimisation
• Compound destructuring

Caveats

• Bublé assumes you're using the class keyword correctly – it doesn't stop you from instantiating a class without new, for example, and doesn't quite adhere to the spec as regards enumerability of methods, etc. Think of Babel's 'loose' mode, except looser.

Is it finished?

Hell no. Still to come:

• More tests, especially for sourcemap support
• Errors for all unsupported features
• A better CLI
• Equivalents of babel-node and babel-register
• An API for controlling what gets transpiled, based on target environment

Please send in your bug reports and pull requests.

Why not just use Babel?

I love Babel: it's an amazing project that has changed how the world writes JavaScript, and I'm in awe of the people who created and maintain it. But it adds overhead and configuration complexity, and so it's not the right tool for every project. Personally, I became frustrated at how much longer my builds took when Babel got involved, and the amount of time it would take to set it up with new projects.

Bublé is an ES2015 compiler that I built to serve my needs and opinions – a no-frills, easy-to-use tool that handles the subset of ES2015 that I actually use (which excludes for...of, generators, and other things that don't transpile well). It doesn't attempt to boil the ocean. If you share my needs and opinions, you will prefer Bublé; if you don't, you should continue to use Babel, which is more complete, more mature, and better supported.

License

MIT

Changelog

0.6.7

• Support static get and set in classes (#34)
• Support spread operator in expression method call (!14)
• Fix for-of loops with no space after opening paren (#35)