create commands in disocrd.js
const { prefix, token } = require('./config.json');
// ...
client.login(token);
//........................................
client.on('message', message => {
if (message.content === `${prefix}ping`) {
message.channel.send('Pong.');
} else if (message.content === `${prefix}beep`) {
message.channel.send('Boop.');
}
});