how to make the bot respond to pings discord.js code example

Example: how to make a ping in discord.js

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`);
        });
    }