Error Logging

// Method 1: Simple error logger
class ErrorLogger {
    log(error, level = 'error') {
        const logEntry = {
            level: level,
            message: error.message,
            stack: error.stack,
            timestamp: new Date().toISOString()
        };
        
        console[level](JSON.stringify(logEntry, null, 2));
    }
}

const logger = new ErrorLogger();
try {
    throw new Error('Test error');
} catch (error) {
    logger.log(error);
}

// Method 2: Structured logging
class StructuredLogger {
    log(error, metadata = {}) {
        const logEntry = {
            error: {
                name: error.name,
                message: error.message,
                stack: error.stack
            },
            metadata: metadata,
            timestamp: new Date().toISOString(),
            environment: 'production'
        };
        
        console.error(JSON.stringify(logEntry));
    }
}

// Method 3: Error levels
const LogLevel = {
    DEBUG: 'debug',
    INFO: 'info',
    WARN: 'warn',
    ERROR: 'error',
    FATAL: 'fatal'
};

class LeveledLogger {
    log(error, level = LogLevel.ERROR) {
        const entry = {
            level: level,
            error: error.message,
            timestamp: Date.now()
        };
        
        if (level === LogLevel.ERROR || level === LogLevel.FATAL) {
            entry.stack = error.stack;
        }
        
        console.log(JSON.stringify(entry));
    }
}

// Method 4: Error aggregation
class ErrorAggregator {
    constructor() {
        this.errors = new Map();
    }
    
    log(error) {
        const key = error.message;
        if (this.errors.has(key)) {
            this.errors.get(key).count++;
        } else {
            this.errors.set(key, {
                message: error.message,
                count: 1,
                firstSeen: Date.now(),
                lastSeen: Date.now()
            });
        }
    }
    
    getSummary() {
        return Array.from(this.errors.values());
    }
}

const aggregator = new ErrorAggregator();
aggregator.log(new Error('Network error'));
aggregator.log(new Error('Network error'));
console.log('Summary:', aggregator.getSummary());