phpnode

type Linkable = {
  name: string,
  profileURL: string
};

function bigOldObject () {
  return {
    id: 1,
    name: 'foo',
    email: 'foo@bar.com',

phpnode

// paste me into https://codemix.github.io/flow-runtime/#/try
// (no gist support yet :( )

import t, {reify} from 'flow-runtime';

type ValidURL = string;

(reify: ValidURL).addConstraint(url => {
  if (/^(.|\/)/.test(url)) {
     return "Don't use relative URLs for some reason"; 

phpnode

// @flow

const proxyCache = new WeakMap();
const extensionMethods = new WeakMap();

function extended<T>(instance: T): $Supertype<T> {
  if (isPrimitive(instance)) {
    return instance;
  }
  const existingProxy = proxyCache.get(instance);

phpnode

const invalidMatchSignal = new Error();

function makeProxyThrower(input) {
  return new Proxy(input, {
    get(target, prop, receiver) {
      if (prop in target) {
        const result = Reflect.get(target, prop, receiver);
        if (typeof result === "object" && result !== null) {
          return makeProxyThrower(result);

phpnode

 function createApprovalMachine(context) {
    return Machine({
        id: 'approval',
        initial: 'initializing',
        context,
        states: {
            initializing: {
                on: {
                    '': [

phpnode

About

In a quest to explore improvements over common JSX transformers I have managed to find great performance able to compete with template literal based libraries.

In this document I would like to describe, via JS itself, and as PoC, how JSX could be both rebranded as ESX and improved.

Goal

Differently from E4X, but also differently from JSX, this proposal leaves developers provide their own "render" implementation, freeing ESX usage from any previous attempt to confine JSX or E4X into the DOM world, where it's been proven, in the JSX case, it's not really where it belongs, as it can be used as neutral DSL.