index.js

// ================= EXPRESS APP HERE ===================
const express = require("express");

const app = express();
const port = process.env.PORT | 3000;

app.listen(port, () => console.log(`Listening on http://localhost:${port}`));
app.get("/", (req, res) => res.send("Sal-kun is Hosted on Repl.it"))

// ================= DISCORD BOT HERE ===================
console.log("Beep boop! 🤖");
const commandHandler = require("./commands");
require("dotenv").config();

const Discord = require("discord.js");
const client = new Discord.Client();
client.login(`${process.env.BOT_TOKEN}`);

client.on("ready", () => {
    console.log("I'm Ready! >.<");
    client.user.setStatus("idle");
    client.user.setActivity("sal help", {
        type: "LISTENING"
    });
});
client.on("message", (msg) => {
    // If we mention the bot alone i.e. "@Sal-kun Bot" and nothing else, we have botMention.
    botMention = (msg.content.startsWith(`<@!${client.user.id}`) || msg.content.startsWith(`<@${client.user.id}`)) && msg.content.endsWith(">");
    if (botMention) {
        let str =
            "Hey looks ike you mentioned me. Well my prefix is sal.\n\n" +
            "You can try `sal help` to see the help menu."
        const prefixEmbed = new Discord.MessageEmbed()
            .setDescription(str)
            .setColor("#f89e4f");
        msg.channel.send(prefixEmbed);
        return;
    }

    // make evrything lower case and check if it starts with sal.
    let content = msg.content.toLowerCase();
    if (!(/^sal$/g.test(content) || /^sal /g.test(content))) return;

    // parses the content.
    const withoutPrefix = msg.content.slice(4);
    const split = withoutPrefix.split(/ +/);
    const cmd = split[0].toLowerCase();
    const args = split.slice(1);

    // Send it to command handler.
    commandHandler(client, msg, cmd, args);
});