How to only allow certian roles ot use this command - node.js

Question

I'm trying to only allow people with the Staff role to run this command.
Basically what the command does, is allowing a bot to DM users
the command is <prefix>send #RandomUserName <message>
I am trying to prevent random users from abusing this command to flood other players DMs.
client.on('message', message => {
if (!message.content.startsWith(prefix) || message.author.bot) return;
const args = message.content.slice(prefix.length).trim().split(/ +/);
const command = args.shift().toLowerCase();
if (message.member.roles.cache.some(role => role.name === 'Staff')) return;
if (command === 'send'){
function getUserFromMention(mention) {
if (!mention) return;
if (mention.startsWith('<#') && mention.endsWith('>')) {
mention = mention.slice(2, -1);
if (mention.startsWith('!')) {
mention = mention.slice(1);
}
return mention;
}
}
const user = getUserFromMention(args[0])
let MessageDM = args[1]
client.users.cache.get(user).send(MessageDM);
}
// ...
});

Answer 1

You're missing a negation (!) in your role-check. Your current if only evaluates to true, when the role is present. But you want to return if the role is not present.
Change your line
if (message.member.roles.cache.some(role => role.name === 'Staff')) return;
to
if (!message.member.roles.cache.some(role => role.name === 'Staff')) return;
Also, as I mentioned in my comment, putting a function inside an if is never a good idea. I'd just put it into the upper scope:
function getUserFromMention(mention) {
if (!mention) return;
if (mention.startsWith('<#') && mention.endsWith('>')) {
mention = mention.slice(2, -1);
if (mention.startsWith('!')) {
mention = mention.slice(1);
}
return mention;
}
}
client.on('message', message => {
if (!message.content.startsWith(prefix) || message.author.bot) return;
const args = message.content.slice(prefix.length).trim().split(/ +/);
const command = args.shift().toLowerCase();
if (!message.member.roles.cache.some(role => role.name === 'Staff')) return;
if (command === 'send'){
const user = getUserFromMention(args[0]);
let MessageDM = args[1];
client.users.cache.get(user).send(MessageDM);
}
// ...
});