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Debugging in discord.js

With discord.js, you can utilize the “debug” and “error” events for debugging. Here’s an example: 
// The client listens for a 'debug' event
client.on('debug', (info) => {
    // Logs the debug info to the console
    console.log(`Debug Info: ${info}`);
});

// The client listens for an 'error' event
client.on('error', (error) => {
    // Logs the error message to the console
    console.error(`Encountered an Error: ${error.message}`);
});
In this code, we use the ‘debug’ event; it is triggered to provide general debugging information, and the debug messages are logged to the console. Similarly, when the ‘error’ event is triggered, the error message is logged to the console.

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Debugging in discord.py

With discord.py, you can use the logging module for debugging. Here’s an example: 
import logging
import logging.handlers

# Sets up the logger for discord
logger = logging.getLogger('discord')
logger.setLevel(logging.DEBUG)
logging.getLogger('discord.http').setLevel(logging.INFO)

# Sets up the handler for the logger
handler = logging.StreamHandler()
dt_fmt = '%Y-%m-%d %H:%M:%S'
formatter = logging.Formatter('[{asctime}] [{levelname:<8}] {name}: {message}', dt_fmt, style='{')
handler.setFormatter(formatter)
logger.addHandler(handler)

# Runs the bot
client.run("your token here", log_handler=None)
In this code, all debugging information and errors are logged to the console.