这行得通
this code worked for me finally `client.on('message', message => {
if (!message.content.startsWith(prefix) || message.author.bot) return;
const args = message.content.slice(prefix.length).split(/ +/);
console.log(args);
const command = args.shift().toLowerCase();
if (command == 'activate') {
const member = message.mentions.members.first(); // Note that first is a method, not a property.
if (!member) return message.channel.send("member not found");
const drole = message.guild.roles.cache.get('842121300532920362');
const prole = message.guild.roles.cache.get('842121301777973298');
const lrole = message.guild.roles.cache.get('842121302708977694');
const frole = message.guild.roles.cache.get('842121305854836826');
member.roles.add(drole);
member.roles.add(lrole);
member.roles.add(prole);
member.roles.remove(frole);
message.channel.send('activated' + ' <' + '@' + member + '>');
}
});`