Refactor: convert to ESM module (.js files) #19719

var mod = require('mod'); =>

• if mod is callable then import mod from 'mod'
• else mod is not callable the import { a, b } from "mod" and replace mod.a and mod.b
• namespace import should ever be used?

var mod= require('mod').a; => import { a } from "mod";

const { a } = require('mod'); => import { a } from "mod";

if (__DEV__) { var warning = require('warning'); }

• disallowed?
• have two actions? one sync and one async?

function f() { var warning = require('warning'); } => async function f() { var warning = await import('warning'); }

• maybe do nothing here as well

module.exports = EventPlugin; => export default EventPlugin;

module.exports.blah = 0 => export const blah = 0

• should we support this too

  var myModule = module.exports = exports = {};
  myModule.a = 0;
  

• this is another common pattern in CJS modules that we should consider supporting
• we already have handling for this in the binder in .js files

module.exports = require('mod'); => export * from 'mod';

module.exports = {foo: function () { } ... } => export function foo() {} ?

• is this even common enough to support?