Explanation of composer.drop()

[Ludenser]

Hi, can you explain to me how this method works? What is the Predicate in argument ? In my bot in scene i would like dynamically adding and dropping handlers for the same action. composer.on('text') for example. Is it real when scene already registered?

[MKRhere]

A predicate is a condition function that returns a boolean. For example, the function passed to Array#filter is a predicate. Composer.drop() takes a predicate which tells Telegraf to drop the matching updates and not process them.

bot.drop(ctx => ctx.chat?.id === blackListedChatId)

For example, this middleware will drop all updates from a blacklisted chat.

dynamically adding and dropping handlers

Composer.drop does not seem the right tool for this. You probably just want to conditionally process updates.

const filter = (ctx, next) => mustReadText && next();

composer.on("text", filter, ctx => {
  // do stuff only when mustReadText is true
}