babelify

What is babelify?

Babelify is a browserify transform for Babel, which allows you to use Babel to transpile your JavaScript files when bundling them with Browserify. This enables you to use the latest JavaScript features and syntax in your code, and have them transpiled to a version of JavaScript that is compatible with older browsers.

What are babelify's main functionalities?

Transpile ES6 to ES5

This feature allows you to transpile modern JavaScript (ES6) to ES5, making it compatible with older browsers. The code sample demonstrates how to use Babelify with Browserify to transform a source file using the '@babel/preset-env' preset.

const browserify = require('browserify');
const babelify = require('babelify');

browserify('./src/app.js')
  .transform(babelify, { presets: ['@babel/preset-env'] })
  .bundle()
  .pipe(process.stdout);

Use JSX with React

This feature allows you to use JSX syntax with React. The code sample shows how to configure Babelify to transform a JSX file using the '@babel/preset-react' preset.

const browserify = require('browserify');
const babelify = require('babelify');

browserify('./src/app.jsx')
  .transform(babelify, { presets: ['@babel/preset-react'] })
  .bundle()
  .pipe(process.stdout);

Custom Babel Plugins

This feature allows you to use custom Babel plugins. The code sample demonstrates how to use the '@babel/plugin-transform-arrow-functions' plugin to transform arrow functions in your code.

const browserify = require('browserify');
const babelify = require('babelify');

browserify('./src/app.js')
  .transform(babelify, { plugins: ['@babel/plugin-transform-arrow-functions'] })
  .bundle()
  .pipe(process.stdout);

Other packages similar to babelify

babel-loader

Babel-loader is a webpack loader that allows you to transpile JavaScript files using Babel and webpack. It is similar to Babelify in that it uses Babel to transpile code, but it is designed to work with webpack instead of Browserify.

rollup-plugin-babel

Rollup-plugin-babel is a Rollup plugin that allows you to use Babel to transpile your JavaScript files when bundling them with Rollup. It provides similar functionality to Babelify but is designed to work with Rollup instead of Browserify.

gulp-babel

Gulp-babel is a Gulp plugin that allows you to use Babel to transpile your JavaScript files in a Gulp build pipeline. It offers similar functionality to Babelify but is intended for use with Gulp instead of Browserify.

README

babelify

Babel browserify transform.

As of Babel 6.0.0 there are no plugins included by default. For babelify to be useful, you must also include some presets and/or plugins.

Installation

$ npm install --save-dev babelify

Usage

CLI

  $ browserify script.js -o bundle.js -t [ babelify --presets [ es2015 react ] ]

Node

var fs = require("fs");
var browserify = require("browserify");
browserify("./script.js")
  .transform("babelify", {presets: ["es2015", "react"]})
  .bundle()
  .pipe(fs.createWriteStream("bundle.js"));

NOTE: Presets and plugins need to be installed as separate modules. For the above examples to work, you'd need to also install babel-preset-es2015 and babel-preset-react:

$ npm install --save-dev babel-preset-es2015 babel-preset-react

Options

Selected options are discussed below. See the babel docs for the complete list of options.

Options may be passed in via standard browserify ways:

$ browserify -t [ babelify --presets [ es2015 react ] ]

browserify().transform("babelify", {presets: ["es2015", "react"]});

var babelify = require("babelify");
browserify().transform(babelify, {presets: ["es2015", "react"]});

Or, with the configure method:

browserify().transform(babelify.configure({
  presets: ["es2015", "react"]
}));

Customizing extensions

By default, all files with the extensions .js, .es, .es6 and .jsx are compiled. You can change this by passing an array of extensions.

NOTE: This will override the default ones so if you want to use any of them you have to add them back.

browserify().transform("babelify", {extensions: [".babel"]});

$ browserify -t [ babelify --extensions .babel ]

Now you can use:

import NavBar from "nav-bar.babel";
var Panels = require("panels.babel");

NOTE: By default, Browserify will only lookup .js and .json files when the extension is ommited (like node's require). To lookup additional extensions, use browserify's extensions option.

browserify({
  extensions: [".babel"]
}).transform("babelify", {
  extensions: [".babel"]
});

$ browserify --extensions=.babel -t [ babelify --extensions .babel ]

Now you can omit the extension and compile .babel files:

import NavBar from "nav-bar";
var Panels = require("panels");

Source maps

By default, browserify sets the source map sources paths relative to the basedir (or to process.cwd() if not set). To make the sources paths absolute, set the sourceMapsAbsolute option on babelify:

browserify().transform("babelify", {
  sourceMapsAbsolute: true
});

$ browserify -t [ babelify --sourceMapsAbsolute ]

Additional options

browserify().transform(babelify.configure({
  // Optional ignore regex - if any filenames **do** match this regex then
  // they aren't compiled
  ignore: /regex/,

  // Optional only regex - if any filenames **don't** match this regex
  // then they aren't compiled
  only: /my_es6_folder/
}))

$ browserify -t [ babelify --ignore regex --only my_es6_folder ]

Babel result (metadata and others)

Babelify emits a babelify event with Babel's full result object as the first argument, and the filename as the second. Browserify doesn't pass-through the events emitted by a transform, so it's necessary to get a reference to the transform instance before you can attach a listener for the event:

var b = browserify().transform(babelify);

b.on("transform", function(tr) {
  if (tr instanceof babelify) {
    tr.once("babelify", function(result, filename) {
      result; // => { code, map, ast, metadata }
    });
  }
});

FAQ

Why aren't files in node_modules being transformed?

This is the default browserify behavior.

A possible solution is to add:

{
  "browserify": {
    "transform": ["babelify"]
  }
}

to the root of all your modules package.json that you want to be transformed. If you'd like to specify options then you can use:

{
  "browserify": {
    "transform": [["babelify", { "presets": ["es2015"] }]]
  }
}

Another solution (proceed with caution!) is to run babelify as a global transform. Use the babel ignore option to narrow the number of files transformed:

browserify().transform("babelify", {
  global: true,
  ignore: /\/node_modules\/(?!app\/)/
});

The above example will result in a transform that also includes the app module in node_modules: the global flag transform all files, and the ignore regular expression then excludes all those in the node_modules directory except those that are in node_modules/app (since ?! will match if the given suffix is absent).

Why am I not getting source maps?

To use source maps, enable them in browserify with the debug option:

browserify({debug: true}).transform("babelify");

$ browserify -d -t [ babelify ]

If you want the source maps to be of the post-transpiled code, then leave debug on, but turn off babelify's sourceMaps:

browserify({debug: true}).transform("babelify", {sourceMaps: false});

$ browserify -d -t [ babelify --no-sourceMaps ]