@episource/babel-preset

A babel preset for transforming your JavaScript for Episource.

Currently contains transforms for all stage 4 (ES2018) and stage 3 syntax. Additionally, stage 4 syntax that is excluded is as follows:

• generators: regenerator-runtime is too heavyweight for our use.
• async/await: regenerator-runtime is too heavyweight for our use, and async-to-promises is not yet complete enough to be safely used.
• async iterators: depends on both generators and async functions
• lifted template literal restrictions: we do not use tagged template literals, nor implement custom DSLs, otherwise we would enable this.

Install

To install with all necessary peerDependencies, use install-peerdeps:

npx install-peerdeps --dev @episource/babel-preset

Usage

Via .babelrc (Recommended)

.babelrc

{
  "presets": ["@episource/babel-preset"]
}

Via CLI

$ babel script.js --presets episource

Via Node API

require('@babel/core').transform('code', {
  presets: ['@episource/babel-preset']
});

Targeting Environments

This module uses @babel/preset-env to target specific environments.

Please refer to @babel/preset-env#targets for a list of available options.

For a list of browsers please see browserlist.

You may override our default list of targets by providing your own targets key.

{
  "presets": [["@episource/babel-preset", {
    "targets": {
      "chrome": 50,
      "ie": 11,
      "firefox": 45
    }
  }]]
}

The following transpiles only for Node v6.

{
  "presets": [["@episource/babel-preset", {
    "targets": {
      "node": 6
    }
  }]]
}

If you wish, you can also inherit our default list of browsers and extend them using additionalTargets.

{
  "presets": [["@episource/babel-preset", {
    "additionalTargets": {
      "chrome": 42,
      "ie": 8
    }
  }]]
}

You may override our default debug option by providing your own debug key.

{
  "presets": [["@episource/babel-preset", {
    "debug": true
  }]]
}

React Development Mode

When process.env.NODE_ENV is 'development', the development mode will be set for @babel/preset-react.

You may override our default development option by providing your own boolean development key.

{
  "presets": [["@episource/babel-preset", {
    "development": false
  }]]
}

React PropTypes removal

This preset can be configured to remove propTypes using babel-plugin-transform-react-remove-prop-types with the following default options:

To enable this transformation with the default options, set the removePropTypes option to true:

{
  "presets": [["@episource/babel-preset", {
    "removePropTypes": true
  }]]
}

The default options that will be used are:

{
  mode: 'wrap',
  additionalLibraries: ['episource-prop-types'],
  ignoreFilenames: ['node_modules'],
}

Default options can be overridden using the removePropTypes option. These options will be shallow-merged with the defaults:

{
  "presets": [["@episource/babel-preset", {
    "removePropTypes": {
      "mode": "remove"
    }
  }]]
}

For example, if you are using this plugin in a deployable app, you might want to use the remove mode for your production build (and disable this transform entirely in development for optimal build speeds).

Classes loose mode

By default, this preset will compile classes in normal mode. This is safer, but comes with a bundle size and runtime overhead. To compile classes in loose mode, set the looseClasses option to true:

{
  "presets": [["@episource/babel-preset", {
    "looseClasses": true,
  }]]
}

The risks of enabling loose classes are outlined in the Babel docs.