Q:

JS command disallow letters, only allow numbers (disc bot)

I've probably looked myself blind on this.  However, i am working on a DiscordJS bot - that has a point system, and can use a ! give to pass on points from user A to user B.
The point passing itself works fine, so that's not the focus point here. 

Issue is that, if i write:

! give @Username 100 
  - it does as expected, it transfers 100 to MENIX. 

"Sent 100 from @MENIX to @Usernames's account"

Then now, what if i write:

! give @Username Dog  - Then it returns; 

"Sent dog from @MENIX to @Usernames's account"

The case is here, i want an error to print if the user inputs anything else than numbers - letters, sentences etc should return error (Ea, you cant dog ! give @username dog)

The current full script is as following
const Discord = require("discord.js");
const functions = require('.././functions.js')
module.exports.run = async (bot, message, args, con, canUseCommand, config) => {

    if (! message.member.roles.some(r => ["Admin"].includes(r.name)))
        return message.reply("Sorry, you don't have permissions to use this!"); 
    let target = message.mentions.users.first()
    let user = message.author
    let points = args[1]

    if (args[1]) {
            await con.query(`SELECT * FROM pts WHERE id = '${message.author.id}'`, async (err, rows) => {
                functions.addCounter();
                let points2 = Math.round(rows[0].points);

                if (! target) {
        return message.channel.send(`Couldn't find user.  Please remember to @ Tag the user & Try again! `)
    }

     if (! args[0]) {
        return message.channel.send(`Woops, looks like you forgot to specify an amount to give`)
    }

     if (message.content.includes('-')) { //tries to remove negative point giving
        return message.channel.send(`Negative points can not be given. `)
    }

        if (points2 < points) {
        return message.channel.send(`Oops trying to give too much points ${message.author}.  You currently have :moneybag: ${functions.formatNumber(points2)} . `)
    }

    await functions.removeMoney(user, points,"remove-points", con)
    await functions.addMoney(target, points,"addpoints", con)

    message.channel.send(`Sent ${points} from ${message.author} to ${target.toString()}'s account`)

    })

}
}

module.exports.help = {
    name: "give"
}

I've tried to play around with the (message.content.includes) but i wasn't able to find a suitable answer for my own question. 
I hope anyone has ideas on how only allow a number input, and if user writes a word / sentence - it will return an error message, that the input is invalid. 

A:

isNaN() function. 
isNaN() – Stands for “is Not a Number”, if variable is not a number, it return true, else return false. 
 if(isNaN(points)) return message.reply("Error");

