Discord.js Triva Bot问题

Question

我正在开发一个简单的Discord Trivia机器人（使用Discord.js）。我正在使用下面的代码，但是Glitch给我错误，提示userAnswer is not defined和answered is not defined等 该代码应选择一个随机问题，然后提出问题并等待答案，然后说出是对还是错。我不知道为什么会发生错误。

任何帮助将不胜感激。

const Discord = require("discord.js")
const { Client, MessageAttachment, MessageEmbed, MemberAdd, RichEmbed } = require('discord.js'); 
const client = new Client(); 

client.on("ready", () => {
    client.user.setActivity("ihs help",{
        type:"STREAMING",
        url:"https://www.twitch.tv/ihsbot"
    })
    console.log("I am ready!");

client.on("guildMemberAdd", member => {
  member.send(
    "Welcome to the server! Please follow our server's rules. Have fun! ?"
  )
})

client.on('message', message, msg => {
  if (answered == false) {
    userAnswer = msg;
    if (userAnswer == cAnswer) {
      message.reply ("got it right!")
    }
    else {
      message.reply ("got it wrong!")
    }
    answered = true; cAnswer = ""; userAnswer = "";
  }

  if (msg.startsWith("ihs quiz")) {
    answered = true;
    cAnswer = "";
    userAnswer = "";
    number = 3;
    random = Math.floor (Match.random() * (number - 1 + 1)) + 1;
    switch (random) {
      case 1: message.channel.send ("**Question** n\A) Answer1 n\B) Answer2 n\C) Answer3 n\D) Answer4"); cAnswer = "a"
      case 2: message.channel.send ("**Question** n\A) Answer1 n\B) Answer2 n\C) Answer3 n\D) Answer4"); cAnswer = "a"
      case 3: message.channel.send ("**Question** n\A) Answer1 n\B) Answer2 n\C) Answer3 n\D) Answer4"); cAnswer = "a"
    }
    answered = false;
  }
});

client.login("TOKEN");

Answer 1

Node.JS与PHP不一样，您可以在其中将值放入变量，但是必须首先声明它，它有3种主要类型：const =常量变量，您不更改，let和var =变量，可以更改，有关这方面的更多信息，这是一篇不错的文章What's the difference between using "let" and "var"?。要声明变量，请执行var varName（与let和const相同）。