index.js

const config = {
"commands": {
    "directory": "/path/to/commands", //path to commands folder
    "subcategories": "false" //if commands are divided by folders change to "true"
  },
  "bot": {
    "token": "bot_token_here"
  }    
}

const Discord = require('discord.js');
const client = new Discord.Client();
const Slash = require('da-slash');
const slash = new Slash.Client(client, config);

client.once('ready', () => {
  //updates Commands
  slash.postCommands();
})

//emitted when a slash command is detected
client.ws.on('INTERACTION_CREATE', async request => {
  const interaction = new Slash.Interaction(client, request);
  //finds the matching slash command and executes it
  slash.matchCommand(interaction); 
})

client.login(config.bot.token);

commandOne.js

const Slash = require('da-slash');
module.exports = new Slash.GlobalCommand({
  name: 'echo',
  description: 'sends a message',
  permissions: ["SEND_MESSAGES"],
  options: [{
    "name": "content",
    "description": "message the bot will send",
    "type": 3 // Type 3 is string
  }],
  execute(interaction) {
    // access discord.Client() through interaction.client
    const client = interaction.client;
    // access the data related to the slash command emitted
    const request = interaction.request;
    // access the arguments passed
    const content = request.data.options.find(arg => arg.name === "content").value;
    // sends message containing the argument
    interaction.sendMessage(content);
  }
})

commandTwo.js

const Slash = require('da-slash');
module.exports = new Slash.GuildCommand({
  name: 'hello',
  description: 'sends a hello message',
  guilds: ["GuildIdHere"],
  permissions: ["SEND_MESSAGES"],
  execute(interaction) {
    interaction.sendMessage("hello");
  }
})