Application

This page describes Application in zalo-bot-js, a handler-based dispatcher class used with ApplicationBuilder, CommandHandler, and MessageHandler.

Different from the event listener API on Bot, Application allows you to add a list of handlers and let the app choose the first suitable handler for each update.

Role

Application holds:

• a bot
• list handlers
• dispatch logic updates to the first matching handler

Main functions

addHandler(handler): void

Add a handler to the handler list.

processUpdate(update): Promise<void>

Iterate through the handlers in order, running the first handler with checkUpdate(update) and returns true.

runPolling(options?): Promise<void>

Run polling through bot.startPolling() and move each update into Application.processUpdate().

stop(): void

Stop current polling by calling bot.stopPolling().

For example

import "dotenv/config";
import { ApplicationBuilder, CommandHandler } from "zalo-bot-js";

const app = new ApplicationBuilder()
  .token(process.env.ZALO_BOT_TOKEN!)
  .build();

app.addHandler(new CommandHandler("start", async (update) => {
  await update.message?.replyText("Xin chào!");
}));

void app.runPolling();

When should you use it?

• want to organize bots using handlers
• want to apply filter and command parser clearly
• want to coordinate updates according to handler order

Next

• See ApplicationBuilder to initialize the app.
• See MessageHandler and CommandHandler to add specific handlers.

Last updated: April 5, 2026