save roles

const members = JSON.parse(fs.readFileSync("./members.json")) || {};
client.on('ready', () => {
  console.log(`Logged in as ${client.user.tag}!`);
  client.guilds.forEach(g=> !members[g.id] ? members[g.id] = {} : null)
});

client.on("guildMemberRemove", member=>{
  let roles = [];
  member.roles.forEach(r=> roles.push(r.id));
  members[member.guild.id][member.id] = roles;
  saveChanges();
});
client.on("guildMemberAdd", member=> {
  if(members[member.guild.id][member.id] !== undefined){
    member.addRoles(members[member.guild.id][member.id], "Returning roles after leaving");
    members[member.guild.id][member.id] = [];
  };
  saveChanges();
});
function saveChanges(){
  fs.writeFileSync("./members.json", JSON.stringify(members, null, 4));
};