Problem: Add Feature-Flagged Logger Instantiation

Easy

15 min

Create a logger factory that selects transports based on feature flags.

Problem statement

You’re rolling out a new remote logging service. In the meantime, some environments still use the existing file logger. Feature flags control which version is enabled. You need to centralize this logic in a factory, so the rest of the system can just call createLogger(flags). The flags object may include { useRemote: true } or { useRemote: false }.

Goal

Implement createLogger(flags) to return a new instance of either FileLogger or RemoteLogger, based solely on the useRemote flag.

Constraints

Do not use conditionals (if, switch, ternaries) to select which class to instantiate.
Do not instantiate loggers outside the factory.
The logger classes must be treated as interchangeable by consumers.

Sample output

The examples below illustrate what the output should look like:

Problem: Add Feature-Flagged Logger Instantiation

Easy

15 min

Create a logger factory that selects transports based on feature flags.

Problem statement

Goal

Implement createLogger(flags) to return a new instance of either FileLogger or RemoteLogger, based solely on the useRemote flag.

Constraints

Do not use conditionals (if, switch, ternaries) to select which class to instantiate.
Do not instantiate loggers outside the factory.
The logger classes must be treated as interchangeable by consumers.

Sample output

The examples below illustrate what the output should look like:

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Node.js

class FileLogger {
  log(msg) {
    return `File: ${msg}`;
  }
}
class RemoteLogger {
  log(msg) {
    return `Remote: ${msg}`;
  }
}
// Implement this
function createLogger(flags) {
  // return appropriate logger instance
}
// Example usage
const remoteLogger = createLogger({ useRemote: true });
console.log(remoteLogger.log('User signed in'));
/* Expected output:
Remote: User signed in */
const fileLogger = createLogger({ useRemote: false });
console.log(fileLogger.log('User updated profile'));
/* Expected output:
File: User updated profile */