client.on('message', message => {
  var prefix = '-'
  if(message.content.startsWith(prefix + 'mention')) {
    if(!message.member.hasPermission('MANAGE_MESSAGES')) return message.channel.send('you don\'t have premission')
    let args = message.content.split(" ").slice(1).join(" ");
    if(!args) return message.channel.send('please type the message')
    message.channel.send(`@everyone ${args}`)
  }
});