Clean up eventsource initialization (vercel#24015)

Just cleans up some code, doesn't change the underlying mechanism



## Bug

- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added

## Feature

- [ ] Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.

## Documentation / Examples

- [ ] Make sure the linting passes

packages/next/client/dev/amp-dev.js

@@ -1,6 +1,6 @@
 /* globals __webpack_hash__ */
 import EventSourcePolyfill from './event-source-polyfill'
-import { getEventSourceWrapper } from './error-overlay/eventsource'
+import { addMessageListener } from './error-overlay/eventsource'
 import { setupPing } from './on-demand-entries-utils'
 import { displayContent } from './fouc'
 
@@ -68,9 +68,7 @@ async function tryApplyUpdates() {
   }
 }
 
-getEventSourceWrapper({
-  path: `${assetPrefix}/_next/webpack-hmr`,
-}).addMessageListener((event) => {
+addMessageListener((event) => {
   if (event.data === '\uD83D\uDC93') {
     return
   }

packages/next/client/dev/dev-build-watcher.js

@@ -1,4 +1,4 @@
-import { getEventSourceWrapper } from './error-overlay/eventsource'
+import { addMessageListener } from './error-overlay/eventsource'
 
 export default function initializeBuildWatcher(toggleCallback) {
   const shadowHost = document.createElement('div')
@@ -39,8 +39,8 @@ export default function initializeBuildWatcher(toggleCallback) {
   let timeoutId = null
 
   // Handle events
-  const evtSource = getEventSourceWrapper({ path: '/_next/webpack-hmr' })
-  evtSource.addMessageListener((event) => {
+
+  addMessageListener((event) => {
     // This is the heartbeat event
     if (event.data === '\uD83D\uDC93') {
       return

packages/next/client/dev/error-overlay/eventsource.js

@@ -57,13 +57,10 @@ function EventSourceWrapper(options) {
   }
 }
 
+export function addMessageListener(cb) {
+  eventCallbacks.push(cb)
+}
+
 export function getEventSourceWrapper(options) {
-  if (!options.ondemand) {
-    return {
-      addMessageListener: (cb) => {
-        eventCallbacks.push(cb)
-      },
-    }
-  }
   return EventSourceWrapper(options)
 }

packages/next/client/dev/error-overlay/hot-dev-client.js

@@ -28,7 +28,7 @@
 
 import * as DevOverlay from '@next/react-dev-overlay/lib/client'
 import stripAnsi from 'next/dist/compiled/strip-ansi'
-import { getEventSourceWrapper } from './eventsource'
+import { addMessageListener } from './eventsource'
 import formatWebpackMessages from './format-webpack-messages'
 
 // This alternative WebpackDevServer combines the functionality of:
@@ -42,10 +42,10 @@ import formatWebpackMessages from './format-webpack-messages'
 
 let hadRuntimeError = false
 let customHmrEventHandler
-export default function connect(options) {
+export default function connect() {
   DevOverlay.register()
 
-  getEventSourceWrapper(options).addMessageListener((event) => {
+  addMessageListener((event) => {
     // This is the heartbeat event
     if (event.data === '\uD83D\uDC93') {
       return

packages/next/client/dev/on-demand-entries-utils.js

@@ -18,8 +18,10 @@ export function setupPing(assetPrefix, pathnameFn, retry) {
   // close current EventSource connection
   closePing()
 
-  const url = `${assetPrefix}/_next/webpack-hmr?page=${currentPage}`
-  evtSource = getEventSourceWrapper({ path: url, timeout: 5000, ondemand: 1 })
+  evtSource = getEventSourceWrapper({
+    path: `${assetPrefix}/_next/webpack-hmr?page=${currentPage}`,
+    timeout: 5000,
+  })
 
   evtSource.addMessageListener((event) => {
     if (event.data.indexOf('{') === -1) return

packages/next/client/dev/webpack-hot-middleware-client.js

@@ -1,11 +1,7 @@
 import connect from './error-overlay/hot-dev-client'
 
-export default ({ assetPrefix }) => {
-  const options = {
-    path: `${assetPrefix}/_next/webpack-hmr`,
-  }
-
-  const devClient = connect(options)
+export default () => {
+  const devClient = connect()
 
   devClient.subscribeToHmrEvent((obj) => {
     if (obj.action === 'reloadPage') {

packages/next/client/next-dev.js

@@ -5,7 +5,7 @@ import initOnDemandEntries from './dev/on-demand-entries-client'
 import initWebpackHMR from './dev/webpack-hot-middleware-client'
 import initializeBuildWatcher from './dev/dev-build-watcher'
 import { displayContent } from './dev/fouc'
-import { getEventSourceWrapper } from './dev/error-overlay/eventsource'
+import { addMessageListener } from './dev/error-overlay/eventsource'
 import * as querystring from '../next-server/lib/router/utils/querystring'
 
 // Temporary workaround for the issue described here:
@@ -25,7 +25,7 @@ const {
 } = window
 
 const prefix = assetPrefix || ''
-const webpackHMR = initWebpackHMR({ assetPrefix: prefix })
+const webpackHMR = initWebpackHMR()
 
 window.next = next
 initNext({ webpackHMR })
@@ -72,7 +72,7 @@ initNext({ webpackHMR })
       }
     }
     devPagesManifestListener.unfiltered = true
-    getEventSourceWrapper({}).addMessageListener(devPagesManifestListener)
+    addMessageListener(devPagesManifestListener)
 
     if (process.env.__NEXT_BUILD_INDICATOR) {
       initializeBuildWatcher((handler) => {