Javascript global variable not working as expected - express

Question

I'm trying to use my "window" variable in express but i cant. Can anyone help
const { app, BrowserWindow } = require("electron")
const expapp = require("express")()
this.window
app.on("ready", () => {
this.window = new BrowserWindow({webPreferences:{ nodeIntegration: true }})
this.window.loadURL("https://www.google.com.tr")
expapp.get("/", (req,res) => {
res.render("index.ejs")
})
/* Sayfayı geri al */
expapp.get("/back", (req,res) => {
this.window.selectPreviousTab()
res.send("ok")
})
})
expapp.listen(1661, () => { console.log("1661 portu üzerinden dinleniyor") })
when i go to this route in express "/back" i get this error
TypeError: this.window.selectPreviousTab is not a function
at C:\Users\GreXLin85\Desktop\Projelerim\PC\xx\app.js:15:21
at Layer.handle [as handle_request] (C:\Users\GreXLin85\Desktop\Projelerim\PC\xx\node_modules\express\lib\router\layer.js:95:5)
at next (C:\Users\GreXLin85\Desktop\Projelerim\PC\xx\node_modules\express\lib\router\route.js:137:13)
at Route.dispatch (C:\Users\GreXLin85\Desktop\Projelerim\PC\xx\node_modules\express\lib\router\route.js:112:3)
at Layer.handle [as handle_request] (C:\Users\GreXLin85\Desktop\Projelerim\PC\xx\node_modules\express\lib\router\layer.js:95:5)
at C:\Users\GreXLin85\Desktop\Projelerim\PC\xx\node_modules\express\lib\router\index.js:281:22
at Function.process_params (C:\Users\GreXLin85\Desktop\Projelerim\PC\xx\node_modules\express\lib\router\index.js:335:12)
at next (C:\Users\GreXLin85\Desktop\Projelerim\PC\xx\node_modules\express\lib\router\index.js:275:10)
at expressInit (C:\Users\GreXLin85\Desktop\Projelerim\PC\xx\node_modules\express\lib\middleware\init.js:40:5)
at Layer.handle [as handle_request] (C:\Users\GreXLin85\Desktop\Projelerim\PC\xx\node_modules\express\lib\router\layer.js:95:5)

Answer 1

You should read about main and renderer processes in electron:
https://www.electronjs.org/docs/tutorial/application-architecture#main-and-renderer-processes
In main process you don't have global window variable: main process is node process, not a browser one.
And BrowserWindow class has no .selectPreviousTab() method - it's not an NSWindow and you are not writing native code in Swift. You should use electron/js documentation not native/Swift documentation ofr developing electron apps.
electron is a framework/platform for writing desktop applications in JS using node and chromium, it is not a native framework.