Structured Logging

Structured logging involves logging in a format that makes it easy to search and analyze logs. JSON is a common structured logging format.

const winston = require('winston');

const logger = winston.createLogger({
  level: 'info',
  format: winston.format.combine(
    winston.format.timestamp(),
    winston.format.json()
  ),
  transports: [
    new winston.transports.Console()
  ]
});

logger.info('User login', { userId: 123, username: 'john_doe' });

Structured logs are easy to query and analyze with tools like Elasticsearch, Kibana, or log aggregators.