type T = { +p: T }; interface T { -p: T }; declare class T { +[k:K]: V }; class T { -[k:K]: V }; class C2 { +p: T = e }; 

// in {['a' + 'b']: 10 * 20, 'z': [1, 2, 3]} // out {ab: 200, z: [1, 2, 3]} 

// install $ npm install babel-plugin-syntax-dynamic-import --save-dev 

// .babelrc { "parserOpts": { "plugins": ['dynamicImport'] } } 

// in var div = <Component {...props} foo="bar" /> // out var div = React.createElement(Component, Object.assign({}, props, { foo: "bar" })); 

function f<T>(x: empty): T { return x; } f(); // nothing to pass... 

// in const [a, b] = [1, 2]; // out var a = 1, b = 2; 

// incorrect, and current gives a unexpected error message { "presets": [ "preset", { "presetOptions": 'hi' } // gets parsed as another preset instead of being part of the "preset" ] } // correct { "presets": [ ["preset", { "presetOptions": 'hi' } ] ] } 

ReferenceError: [BABEL] /test.js: Unknown option: base.loose2. Check out http://babeljs.io/docs/usage/options/ for more information about options. A common cause of this error is the presence of a configuration options object without the corresponding preset name. Example: Invalid: `{ presets: [{option: value}] }` Valid: `{ presets: ["pluginName", {option: value}] }` For more detailed information on preset configuration, please see http://babeljs.io/docs/plugins/#pluginpresets-options. 

var a: Promise<boolean>[]; // instead of var a: Promise<bool>[]; 

// transform-react-inline-elements // issue with imported components that were JSXMemberExpression import { form } from "./export"; function ParentComponent() { return <form.TestComponent />; } 

// transform-react-inline-elements import { Modal } from "react-bootstrap"; export default CustomModal = () => <Modal.Header>foobar</Modal.Header>; 

if ( true ) { loop: for (let ch of []) {} } 

class A { prop1 = () => this; static prop2 = () => this; prop3 = () => arguments; } 

// in class C { async *g() { await 1; } } // out class C { g() { // was incorrectly outputting the method with a generator still `*g(){` return _asyncGenerator.wrap(function* () { yield _asyncGenerator.await(1); })(); } } 

// was wrapping variables in an IIFE incorrectly for ( let i = 0, { length } = list; i < length; i++ ) { console.log( i + ': ' + list[i] ) } 

// was producing invalid code class Ref { static nextId = 0 constructor(id = ++Ref.nextId, n = id) { this.id = n } } assert.equal(1, new Ref().id) assert.equal(2, new Ref().id) 

function first(...values) { let index = 0; return values[index++]; // ++ was happening twice } console.log(first(1, 2)); 

let x = 10; if (1) { ca: let x = 20; } 

a[`${b++}`] **= 1; 

foo = { bar() { return super.baz **= 12; } } 

// @flow var obj = { method(a: string): number { return 5 + 5; } }; 

// @flow class C { m(x: number): string { return 'a'; } }