try using initialize always when available

src/esmock.js

@@ -1,11 +1,15 @@
+import module from 'node:module'
+import threads from 'node:worker_threads'
+import * as hooks from './esmockLoader.js'
+import esmockRegister from './esmockRegister.js'
 import esmockLoader from './esmockLoader.js'
 import esmockModule from './esmockModule.js'
 import esmockArgs from './esmockArgs.js'
 import esmockErr from './esmockErr.js'
 
 const esmockGo = opts => async (...args) => {
   const [moduleId, parent, defs, gdefs, opt] = esmockArgs(args, opts)
-  if (!await esmockLoader())
+  if (!esmockRegister && !await esmockLoader())
     throw esmockErr.errMissingLoader()
 
   const fileURLKey = await esmockModule(moduleId, parent, defs, gdefs, opt)
@@ -31,4 +35,10 @@ const esmock = Object.assign(esmockGo(), {
   purge, p: esmockGo({ purge: false }), strict, strictest })
 
 export {esmock as default, strict, strictest}
-export * from './esmockLoader.js'
+
+
+const isMessageChannel = Boolean(module.register && threads.MessageChannel)
+const hooksFinal = isMessageChannel ? {} : hooks
+const { load, resolve, getSource, initialize, globalPreload } = hooksFinal
+export { load, resolve, getSource, initialize, globalPreload }
+// export * from './esmockLoader.js'

src/esmockLoader.js

@@ -1,4 +1,6 @@
 import fs from 'node:fs/promises'
+import module from 'node:module'
+import threads from 'node:worker_threads'
 import process from 'process'
 import esmockErr from './esmockErr.js'
 
@@ -28,25 +30,27 @@ const hashbangRe = /^(#![^\n]*\n)/
 const moduleIdReCreate = (moduleid, treeid) => new RegExp(
   `.*(${moduleid}(\\?${treeid}(?:(?!#-#).)*)).*`)
 
+const isMessageChannel = Boolean(module.register && threads.MessageChannel)
+
 // node v12.0-v18.x, global
 const mockKeys = global.mockKeys = (global.mockKeys || {})
 
 // node v20.0-v20.6
-const globalPreload = (({ port }) => (
+const globalPreload = !isMessageChannel && (({ port }) => (
   port.addEventListener('message', ev => (
     mockKeys[ev.data.key] = ev.data.keylong)),
   port.unref(),
   'global.postMessageEsmk = d => port.postMessage(d)'
 ))
 
 // node v20.6-current
-const initialize = data => {
+const initialize = isMessageChannel && (data => {
   if (data && data.port) {
     data.port.on('message', msg => {
       mockKeys[msg.key] = msg.keylong
     })
   }
-}
+})
 
 const parseImports = defstr => {
   const [specifier, imports] = (defstr.match(esmkImportRe) || [])
@@ -220,7 +224,7 @@ export {
   getSource,
   // if getSource and initialize exported at the time,
   // getSource is never called :(
-  // initialize,
+  initialize,
   globalPreload,
   loaderIsVerified as default
 }

src/esmockRegister.js

@@ -8,8 +8,8 @@ const register = (res => () => {
   if (typeof res === 'boolean')
     return res
 
-  if (!(res = global.shouldRegister === true))
-    return res
+  //  if (!(res = global.shouldRegister === true))
+  //    return res
 
   if ((res = Boolean(channel && module.register))) {
     module.register('./esmockLoader.js', {