If my message contains a specific thing, how can I make my discord bot read that?

Question

The title may not be very helpful, but what I mean is that if my message says "hello", how can I make my discord bot say hello back, even if the "hello" is not on its own in a single message, and it does not use my bot's prefix?

Answer 1

It's quite simple actually. Let's say you have a command code like this:

client.on("messageCreate", async message => {
  if (message.author.bot) return; //filters out bots

  else if (message.content.startsWith(prefix)){
    const args = message.content.slice(prefix.length).trim().split(/ +/g)
    const commandName = args.shift().toLowerCase();
    const command = await client.commands.get(commandName);
    if (!command) return;
    await command.run(client, message, args);
  } //if starts with prefix run any applicable command

  else if (message.mentions.users.first()===client.user) {
    const helpembed = {
      title: "Help",
      description: "To view help use `+help`!",
    }
    return message.reply({embeds: [helpembed]});
  } //if not starts with prefix but has bot mentioned

});

add another else if statement in there, after the last else if statement:

else if (message.content.includes("hello")) {
   message.reply("hello");
}

note that .includes() is case sensitive.