node.js - JavaScript TypeError: Cannot read property 'startsWith' of undefined - discord bot - Stack Overflow

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I must start this question by saying that I have very little knowledge of javascript (I'm practiced in Java) and just wanted to make a (somewhat) simple Discord bot that would say messages at random times. I Frankensteined 2 pieces of code from various tutorials together and currently have this:

var Discord = require('discord.io');
var logger = require('winston');
var auth = require('./auth.json');
//random bot code
var randomMessage;
var randOn = false;
var responseArray = [ //add more messages here
  "Ayy, lmao!",
  "Say what?",
  "roflmaotntpmp"
];

var prefix = "!";
var timer = [5,10]; //set min and max in seconds for random messages


// Configure logger settings
logger.remove(logger.transports.Console);
logger.add(new logger.transports.Console, {
    colorize: true
});
logger.level = 'debug';
// Initialize Discord Bot
var bot = new Discord.Client({
   token: auth.token,
   autorun: true
});
bot.on('ready', function (evt) {
    logger.info('Connected');
    logger.info('Logged in as: ');
    logger.info(bot.username + ' - (' + bot.id + ')');
});


bot.on('message', (msg) => {

  if (msg.content.startsWith(prefix + "on")) {
        if (randOn) {
            msg.channel.sendMessage("Already running.");
        }
        else {
            msg.channel.sendMessage("Random message started.")
        randomMessage = setTimeout(function() {
                randMsg(msg.channel);
            }, 1000*timer[0]);
        }
  }
  else if (msg.content.startsWith(prefix + "off")) {
        if (randOn) {
            clearTimeout(randomMessage);
            msg.channel.sendMessage("Random message disabled.");
        }
        else {
            msg.channel.sendMessage("Not running.");
        }
  }


});



function randomIntFromInterval(min, max) {
  return Math.floor(Math.random()*(max-min+1)+min);
}

function randMsg(msgChan) {
    console.log("callback");
    var interval = 1000*randomIntFromInterval(timer[0],timer[1]);
  var rand = randomIntFromInterval(0,responseArray.length-1);
  if(responseArray[rand]) {
    msgChan.sendMessage(responseArray[rand]);
  }
    randomMessage = setTimeout(function() {
        randMsg(msgChan);
    }, interval);
}

The problem is occurring in this block:

 bot.on('message', (msg) => {

      if (msg.content.startsWith(prefix + "on")) {
            if (randOn) {
                msg.channel.sendMessage("Already running.");
            }

Every time I attempt to mand the bot in my discord chat (!on) I get the error "TypeError: Cannot read property 'startsWith' of undefined" in Node.js/mand prompt. I've tried various things to fix it (removing "content" from both msg.content... statements - no plaints but absolutely nothing happens) but... I honestly have no idea what I'm doing. I've checked every post on the internet that deals with similar things and nothing has been able to answer this. I'm hoping it's a simple syntax thing/something not declared properly... If you have some time and pity for me, please help. I know I've gotten myself into a mess but I refuse to abandon it!

Let me know what other information I can provide to help.

I must start this question by saying that I have very little knowledge of javascript (I'm practiced in Java) and just wanted to make a (somewhat) simple Discord bot that would say messages at random times. I Frankensteined 2 pieces of code from various tutorials together and currently have this:

var Discord = require('discord.io');
var logger = require('winston');
var auth = require('./auth.json');
//random bot code
var randomMessage;
var randOn = false;
var responseArray = [ //add more messages here
  "Ayy, lmao!",
  "Say what?",
  "roflmaotntpmp"
];

var prefix = "!";
var timer = [5,10]; //set min and max in seconds for random messages


// Configure logger settings
logger.remove(logger.transports.Console);
logger.add(new logger.transports.Console, {
    colorize: true
});
logger.level = 'debug';
// Initialize Discord Bot
var bot = new Discord.Client({
   token: auth.token,
   autorun: true
});
bot.on('ready', function (evt) {
    logger.info('Connected');
    logger.info('Logged in as: ');
    logger.info(bot.username + ' - (' + bot.id + ')');
});


bot.on('message', (msg) => {

  if (msg.content.startsWith(prefix + "on")) {
        if (randOn) {
            msg.channel.sendMessage("Already running.");
        }
        else {
            msg.channel.sendMessage("Random message started.")
        randomMessage = setTimeout(function() {
                randMsg(msg.channel);
            }, 1000*timer[0]);
        }
  }
  else if (msg.content.startsWith(prefix + "off")) {
        if (randOn) {
            clearTimeout(randomMessage);
            msg.channel.sendMessage("Random message disabled.");
        }
        else {
            msg.channel.sendMessage("Not running.");
        }
  }


});



function randomIntFromInterval(min, max) {
  return Math.floor(Math.random()*(max-min+1)+min);
}

function randMsg(msgChan) {
    console.log("callback");
    var interval = 1000*randomIntFromInterval(timer[0],timer[1]);
  var rand = randomIntFromInterval(0,responseArray.length-1);
  if(responseArray[rand]) {
    msgChan.sendMessage(responseArray[rand]);
  }
    randomMessage = setTimeout(function() {
        randMsg(msgChan);
    }, interval);
}

The problem is occurring in this block:

 bot.on('message', (msg) => {

      if (msg.content.startsWith(prefix + "on")) {
            if (randOn) {
                msg.channel.sendMessage("Already running.");
            }

Every time I attempt to mand the bot in my discord chat (!on) I get the error "TypeError: Cannot read property 'startsWith' of undefined" in Node.js/mand prompt. I've tried various things to fix it (removing "content" from both msg.content... statements - no plaints but absolutely nothing happens) but... I honestly have no idea what I'm doing. I've checked every post on the internet that deals with similar things and nothing has been able to answer this. I'm hoping it's a simple syntax thing/something not declared properly... If you have some time and pity for me, please help. I know I've gotten myself into a mess but I refuse to abandon it!

Let me know what other information I can provide to help.

• javascript
• node.js
• bots
• discord.io

Share Improve this question Follow edited Aug 27, 2019 at 14:12 simhumileco 34.8k1717 gold badges147147 silver badges123123 bronze badges asked Nov 16, 2018 at 2:56 lilslils 6111 gold badge11 silver badge55 bronze badges 3

• what is the value of msg when the handler is called? can you console.log(msg) it and share the output? – shkaper Commented Nov 16, 2018 at 3:09
• not sure if I did this right, but I placed "console.log(msg);" right before the start of the if statement containing msg.content...etc. when I ran the bot (node bot.js) and tried to use a mand in discord, it just printed my discord name in mand prompt right before it threw the error @shkaper – lils Commented Nov 16, 2018 at 3:16
• Put in a console.dir(msg) this will give you an exploded dump of the object, including all members and methods. Insert this after the line: bot.on('message', (msg) => { – SPlatten Commented Nov 16, 2018 at 10:00

Add a ment  | 

2 Answers 2

Sorted by: Reset to default 2

Your issue is, that you mix discord.js with discord.io

discord.js is object oriented where discord.io is not, so in discord.io your message is already a string!

Example discord.io message event.

bot.on('message', function(user, userID, channelID, message, event) {
    if (message === "ping") {
        bot.sendMessage({
            to: channelID,
            message: "pong"
        });
    }
});

Maybe jam something like if(!msg || !msg.content) return; in there to bail out if the msg object or its content property is undefined.

bot.on('message', (msg) => {

  if(!msg || !msg.content) return;

  if (msg.content.startsWith(prefix + "on")) {
        if (randOn) {
            msg.channel.sendMessage("Already running.");
        }
        else {
            msg.channel.sendMessage("Random message started.")
        randomMessage = setTimeout(function() {
                randMsg(msg.channel);
            }, 1000*timer[0]);
        }
  }
  else if (msg.content.startsWith(prefix + "off")) {
        if (randOn) {
            clearTimeout(randomMessage);
            msg.channel.sendMessage("Random message disabled.");
        }
        else {
            msg.channel.sendMessage("Not running.");
        }
  }


});

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