If you don't want to use the MongoDB Version checkout the Normal Version
Commands:
npm init
npm install discord.js
npm install moment
npm install enmap
npm install mongoose
Keep in mind, the getPrefix function is using a callback method so if you want to call the function in an other class run the following code:
client.functions.getPrefix(message.guild.id, function(prefix) {
console.log(prefix);
});
Oh yeah and make sure to check if the guild has a prefix using the hasPrefix function! (That one will return true or false)
Don't worry you can see an example of this in the septrefix.js file!