how to make a ping command on a discord bot discord.js

message.channel.send("Getting bot ping...").then(m =>{
    var ping = m.createdTimestamp - message.createdTimestamp;
    var trueping = Math.round(bot.pi);

    m.edit(`Bot latency: ${botPing}`);
});

if(cmd === `${prefix}ping`) {
        message.channel.send("Pinging...").then(m =>{
            var ping = m.createdTimestamp - message.createdTimestamp;
            var botPing = Math.round(bot.pi);

            m.edit(`**:ping_pong: Pong! Your Ping Is:-**\n  ${ping}ms`);
        });
    }

  if(!message.content.startsWith(prefix) || message.author.bot) return;

     const args = message.content.slice(prefix.length).split(/+/);
     const command = args.shift().toLowerCase();

     if(command === 'ping'){
         message.channel.send('pong');
     }