main.js

const { app, BrowserWindow } = require("electron");
const express = require("express");

app.on("ready", function () {
  var ex = express();

  var mainWindow = new BrowserWindow({
    width: 800,
    height: 600,
    webPreferences: {
      nodeIntegration: true,
    },
  });

  ex.get("/whats/:num/:msg", function (req, res) {
    var numero = req.params.num;
    var msg = req.params.msg;
    enviar(numero, msg);
    res.send("enviando Mensagem via whatsapp..");
  });

  function enviar(telefone, mensagem) {
    mainWindow.loadURL(
      "https://web.whatsapp.com/send?phone=" + telefone + "&text=" + mensagem,
      {
        userAgent:
          "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.110 Safari/537.36",
      }
    );
    mainWindow.webContents.executeJavaScript(
      'var{ipcRenderer,remote} = require("electron");var enviado = false;function tempo(){var btsend = document.getElementsByClassName("_2Ujuu")[0];var inputSend = document.getElementsByClassName("_1awRl")[1];if(typeof inputSend !== "undefined" && inputSend.innerText && !enviado){btsend.click();enviado=true;}else if(enviado){ipcRenderer.send("para", {status:true});}}setInterval(tempo,3000);'
    );
    mainWindow.show();
  }
  ex.listen(3400);
});