ESCompress

An ES2015-aware JavaScript minifier built using Babel.

Installation

npm install escompress

Usage

There are two ways to use the base ESCompress package. Both are thin wrappers around the equivalent Babel CLI and API.

ESCompress accepts any options through the CLI and API that are valid for Babel but some of them have different values by default:

| Option | Default | Notes | | ------ | --------| ----- | | babelrc | false | Needed so that it doesn't pick up your existing one | | comments | false | | | compact | 'true' | | | presets | ['escompress'] | Will be merged with any presets passed |

You can of course override these.

CLI

For more information see Babel:

escompress [options] input.js

API

For more information see Babel:

import escompress from 'escompress';

const code = `class Example {}`;
const result = escompress.transform(code, { /* options */ });

result.code; // Generated code
result.map; // Sourcemap
result.ast; // AST

What?

ESCompress is a JavaScript compressor and minifier (and beautifier if you want 💅) that is able to work on ES2015 (and soon beyond) syntax.

At its heart, it's a wrapper around Babel using some plugins to remove and simplify code so that it's ready for production.

Why?

Modern browsers are now approaching almost full implementation of the ES2015 spec. See for yourself here: http://kangax.github.io/compat-table/es6/

We're reaching the point where it's entirely feasible to think about deploying some of this syntax to the browser instead of always transpiling down to ES5. The Webpack creator, @sokra, in his Advanced Frontend Optimization (with Webpack) presentation recommends that we prepare JavaScript files "for every combination". Yes, he mentions ES5 and ES3🕸, but that's because there's a problem: at the moment we can't really compress and minify ES2015/ES6 with UglifyJS (although it is being worked on).

How?

By developing a tool built on Babel we get access to a parser, AST traversal and code generator that supports the latest syntax. All we need to do is provide plugins!

Features

At the moment we're using the following plugins via the ESCompress preset:

• babel-plugin-transform-dead-code-elimination
• babel-plugin-transform-mangle-names
• babel-plugin-transform-merge-sibling-variables
• babel-plugin-transform-minify-booleans
• babel-plugin-transform-undefined-to-void