Discord.js Breaking down Ban Command for Command Handler issues - arguments

Question

I have a rather large index.js so iv been busy stripping it out into individual command files, i have successfully exported all my code into separate commands, all but ban. So far the ban code works as intended, but if a 18 digit user ID is entered, and they have left the server it should check and log it in a .json file but currently its not getting past if (isNaN(args[1])) it just plain wont accept anything, number and or letters all result in "You need to enter a vlaid #Member or UserID #" This is very frustrating as it took me hours to get working within my index.js
run: async (bot, message, args) => {
if (!message.member.hasPermission(["BAN_MEMBERS", "ADMINISTRATOR"])) return message.channel.send("You do not have permission to perform this command!")
const user1 = message.mentions.users.first();
var member = message.mentions.members.first()
if (member) {
const member = message.mentions.members.first()
let reason = args.slice(2).join(' '); // arguments should already be defined
var user = message.mentions.users.first();
member.ban({ reason: `${args.slice(2).join(' ')}` }).then(() => {
let uEmbed = new RichEmbed()
.setTitle('**' + `Sucessfully Banned ${user1.tag}!` + '**')
.setThumbnail('https://i.gyazo.com/8988806671312f358509cf0fd69341006.jpg')
.setImage('https://media3.giphy.com/media/H99r2HtnYs492/giphy.gif?cid=ecf05e47db8ad81dd0dbb6b132bb551add0955f9b92ba021&rid=giphy.gif')
.setColor(0x320b52)
.setTimestamp()
.setFooter('Requested by ' + message.author.tag, 'https://i.gyazo.com/8988806671312f358509cf0fd69341006.jpg')
message.channel.send(uEmbed);
}).catch(err => {
message.channel.send('I was unable to kick the member');
console.log(err);
});
} else {
let user = message.mentions.users.first(),
userID = user ? user.id : args[1]
if (isNaN(args[1])) return message.channel.send("You need to enter a vlaid #Member or UserID #");
if (args[1].length <= 17 || args[1].length >= 19) return message.channel.send("UserID # must be 18 Digits");
if (userID) {
let bannedIDs = require('./bannedIDs.json').ids || []
if (!bannedIDs.includes(userID)) bannedIDs.push(userID)
fs.writeFileSync('./bannedIDs.json', JSON.stringify({ ids: bannedIDs }))
let reason = args.slice(2).join(' ');
let uEmbed = new RichEmbed()
.setTitle('**' + `UserID #${args[1]}\n Will be Banned on Return!` + '**')
.setThumbnail('https://i.gyazo.com/8988806671312f358509cf0fd69341006.jpg')
.setImage('https://i.imgur.com/6Sh8csf.gif')
.setColor(0x320b52)
.setTimestamp()
.setFooter('Requested by ' + message.author.tag, 'https://i.gyazo.com/8988806671312f358509cf0fd69341006.jpg')
message.channel.send(uEmbed);
} else {
message.channel.send('Error')
}
}
}
}

Answer 1

Firstly, if (args[1].length <= 17 || args[1].length >= 19 can be reduced to if(args[1].length !== 18), I saw your other post and it suggests you got passed this bug, is this correct?