Have a default port and only switch to a random one if that's taken

main.js

@@ -2,6 +2,7 @@ const {app, BrowserWindow, shell} = require('electron')
 const path = require('path')
 const express = require('express')
 const eApp = express()
+const portInUse = require('./portInUse.js')
 
 const frontendPath = 'frontend/'
 
@@ -24,15 +25,24 @@ function createWindow() {
 	// Hide the toolbar
 	mainWindow.setMenuBarVisibility(false)
 
-	// Start a local express server to serve static files
+	// We try to use the same port every time and only use a different one if that does not succeed.
-	eApp.use(express.static(path.join(__dirname, frontendPath)))
+	let port = 45735
-	// Handle urls set by the frontend
+	portInUse(port, used => {
-	eApp.get('*', (request, response, next) => {
+		if(used) {
-		response.sendFile(`${__dirname}/${frontendPath}index.html`);
+			console.log(`Port ${port} already used, switching to a random one`)
-	})
+			port = 0 // This lets express choose a random port
-	const server = eApp.listen(0,  '127.0.0.1', () => {
+		}
-		console.log(`Server started on port ${server.address().port}`)
+
-		mainWindow.loadURL(`http://127.0.0.1:${server.address().port}`)
+		// Start a local express server to serve static files
+		eApp.use(express.static(path.join(__dirname, frontendPath)))
+		// Handle urls set by the frontend
+		eApp.get('*', (request, response, next) => {
+			response.sendFile(`${__dirname}/${frontendPath}index.html`);
+		})
+		const server = eApp.listen(port,  '127.0.0.1', () => {
+			console.log(`Server started on port ${server.address().port}`)
+			mainWindow.loadURL(`http://127.0.0.1:${server.address().port}`)
+		})
 	})
 }