HTTP Header Non-ASCII Character Limitation

main.js

// Modules to control application life and create native browser window
const { app, BrowserWindow, protocol, net, session } = require("electron");
const http = require("node:http");

function createWindow() {
  // Create the browser window.
  const mainWindow = new BrowserWindow({
    width: 800,
    height: 600,
    x: 0,
    y: 0,
  });

  mainWindow.loadURL("http://localhost:3000/app");

  const mainWindow2 = new BrowserWindow({
    width: 800,
    height: 600,
    x: 800,
    y: 0,
  });

  mainWindow2.loadURL("http://localhost:3000/sanitized");

  mainWindow2.webContents.setUserAgent(`${mainWindow2.webContents.getUserAgent()}✓`);

  const mainWindow3 = new BrowserWindow({
    width: 800,
    height: 600,
    x: 1600,
    y: 0,
  });

  mainWindow3.loadURL("http://localhost:3000/sanitized");
}

// This method will be called when Electron has finished
// initialization and is ready to create browser windows.
// Some APIs can only be used after this event occurs.
app.whenReady().then(() => {
  protocol.handle("http", (request) => {
    return net.fetch(request, { bypassCustomProtocolHandlers: true });
  });

  session.defaultSession.webRequest.onHeadersReceived(
    { urls: ["*://*/*"] },
    (details, callback) => {
      const responseHeaders = { ...details.responseHeaders };

      responseHeaders["X-Custom-Header"] = ["✓"]; // Adding a non-ASCII character in the header

      if (details.url === "http://localhost:3000/sanitized") {
        // Electron's net.fetch does not support non-ASCII characters in the headers
        for (const [key, value] of Object.entries(responseHeaders)) {
          // normalize and convert all non-ASCII characters to ASCII using Buffer
          responseHeaders[key] = value.map((entry) => {
            const normalized = entry.normalize("NFKD");
            const buffer = Buffer.from(normalized, "utf8");
            return buffer.toString("ascii");
          });
        }
      }

      callback({ responseHeaders });
    }
  );

  const server = http.createServer((_req, res) => {
    res.writeHead(200, {
      "Content-Type": "text/plain",
    });

    res.end("Hello World");
  });

  server.listen(3000, () => {
    console.log("Server is listening on http://localhost:3000");
  });

  createWindow();

  app.on("activate", function () {
    // On macOS it's common to re-create a window in the app when the
    // dock icon is clicked and there are no other windows open.
    if (BrowserWindow.getAllWindows().length === 0) createWindow();
  });
});

// Quit when all windows are closed, except on macOS. There, it's common
// for applications and their menu bar to stay active until the user quits
// explicitly with Cmd + Q.
app.on("window-all-closed", function () {
  if (process.platform !== "darwin") app.quit();
});

// In this file you can include the rest of your app's specific main process
// code. You can also put them in separate files and require them here.

package.json

{
  "name": "numberless-berry-multiply-6vf04",
  "productName": "numberless-berry-multiply-6vf04",
  "description": "My Electron application description",
  "keywords": [],
  "main": "./main.js",
  "version": "1.0.0",
  "author": "Shadax",
  "scripts": {
    "start": "electron ."
  },
  "dependencies": {},
  "devDependencies": {
    "electron": "30.0.6"
  }
}