babel-preset-kensho

babel-preset-kensho

This Babel 7 preset transpiles ES2018, JSX, and selected language proposals to ES5. It also includes optimizations for specific contexts.

Install

npm install -D babel-preset-kensho

Usage

You can set up Babel transpilation in several ways (e.g. via CLI, or through webpack). Choose a method, and configure Babel to include the preset, e.g. in a .babelrc:

{
  "presets": ["kensho"]
}

Options

The preset can be configured using several options. Note that some options' defaults depend on the Babel environment, which may be one of: development | production | test | cjs

lodash

true | false
Default: true

Whether to transpile Lodash imports using babel-plugin-lodash to reduce bundle size.

// false:
import {map, reduce} from 'lodash'

// true:
import map from 'lodash/map'
import reduce from 'lodash/reduce'

loose

true | false
Default: true

Whether to enable loose mode in all presets/plugins that support this option.

modules

false | 'commonjs'
Default: 'commonjs' in cjs/test env, false otherwise

Whether to compile ESM imports/exports to another module format.

// false:
import foo from './foo'

// 'commonjs' (roughly):
const foo = require('./foo')

react

true | false | options
Default: true

Whether to transpile JSX expressions. If an options object is passed, it is forwarded to the React preset.

removePropTypes

'remove' | 'wrap' | 'unsafe-wrap' | false
Default: 'remove' in production env, 'unsafe-wrap' otherwise

Whether to remove React component propTypes assignment to reduce bundle size. When set to 'remove', also removes imports of the prop-types module.

// false:
Foo.propTypes = {bar: PropTypes.string}

// 'wrap':
Foo.propTypes = process.env.NODE_ENV !== 'production' ? {bar: PropTypes.string} : {}

// 'unsafe-wrap':
process.env.NODE_ENV !== 'production' ? (Foo.propTypes = {bar: PropTypes.string}) : void 0

// 'remove':

runtime

true | false
Default: true

Whether to enable the Babel runtime transform. This is encouraged to reduce bundle size, but requires adding @babel/runtime as a dependency.

targets

See @babel/preset-env options documentation.
Default: current node version in test env, recent browsers otherwise

The transpilation targets to pass to @babel/preset-env.

typescript

true | false | options
Default: true

Whether to enable TypeScript support. If an options object is passed, it's passed to the TypeScript preset.

useBuiltIns

true | false
Default: true

Whether to assume the presence of built-in ES2015 methods (e.g. Object.assign) in transpiled output rather than using helper functions. This option assumes that you will be polyfilling a global ES2015 environment if you need to support non-ES2015 browsers.