Configurable log formatting

Design logging systems with customizable formatting and output options. Separate formatting logic into protected methods that can be overridden by derived logger implementations.

Key practices:

1. Use consistent parameter naming (prefer json over asJSON)
2. Separate color handling from message composition
3. Make core formatting components overridable
4. Support environment variables for controlling features like colored output

Example of a well-structured logger with configurable formatting:

```typescript export class CustomizableLogger implements LoggerService { // Allow configuring output format constructor(protected options: { json?: boolean, timestamp?: boolean }) {}

// Core logging implementation log(message: any, context?: string) { const formattedMessage = this.formatMessage(message, context, ‘log’); process.stdout.write(formattedMessage); }

// Protected method for formatting - can be overridden protected formatMessage(message: unknown, context: string, logLevel: string): string { // For JSON output if (this.options.json) { return JSON.stringify({ level: logLevel, message, context, timestamp: new Date().toISOString() }) + ‘\n’; }

// Regular formatted output with optional coloring
const output = this.stringifyMessage(message);
const contextMsg = context ? `[${context}] ` : '';
const timestamp = this.options.timestamp ? this.getTimestamp() : '';
const formattedLevel = this.colorize(logLevel.toUpperCase().padStart(7, ' '));

return `${timestamp} ${formattedLevel} ${contextMsg}${output}\n`;   }

// Helper methods that can also be overridden protected stringifyMessage(message: unknown): string { return typeof message === ‘object’ ? JSON.stringify(message, null, 2) : String(message); }

protected colorize(text: string, color?: (text: string) => string): string { // Default implementation or delegate to provided color function return color ? color(text) : text; }

protected getTimestamp(): string { return new Date().toISOString(); } }