@real-router/logger

Isomorphic structured logger for the Real-Router ecosystem. Level filtering, custom callbacks, works in any JavaScript runtime.

Zero dependencies. Used internally by @real-router/core and plugins.

Installation

npm install @real-router/logger

Quick Start

import { logger } from "@real-router/logger";

logger.log("App", "Application started");
logger.warn("Auth", "Token expires in 5 minutes");
logger.error("API", "Request failed", error);

logger.configure({ level: "error-only" });

API

| Method | Description | |--------|-------------| | logger.log(context, message, ...args) | Informational message | | logger.warn(context, message, ...args) | Warning message | | logger.error(context, message, ...args) | Error message | | logger.configure(config) | Update logger configuration | | logger.getConfig() | Return current configuration |

Log Levels

| Level | log | warn | error | |-------|:---:|:----:|:-----:| | "all" | Yes | Yes | Yes | | "warn-error" | — | Yes | Yes | | "error-only" | — | — | Yes | | "none" | — | — | — |

Configuration

logger.configure({
  level: "warn-error",
  callback: (level, context, message, ...args) => {
    Sentry.captureMessage(`[${context}] ${message}`);
  },
  callbackIgnoresLevel: false, // default: false
});

| Option | Type | Default | Description | |--------|------|---------|-------------| | level | LogLevelConfig | "all" | Which messages to show in console | | callback | LogCallback | — | Custom handler for log messages | | callbackIgnoresLevel | boolean | false | When true, callback receives all messages regardless of level |

callbackIgnoresLevel

Decouples console output from callback — useful for error tracking, metrics, or external logging:

// Console: silent. Callback: everything.
logger.configure({
  level: "none",
  callbackIgnoresLevel: true,
  callback: (level, context, message) => {
    externalLogger.send({ level, context, message });
  },
});

Use Cases

Error Tracking (Sentry)

logger.configure({
  level: "warn-error",
  callback: (level, context, message, ...args) => {
    if (level === "error") {
      Sentry.captureMessage(`[${context}] ${message}`, {
        level: "error",
        extra: { args },
      });
    }
  },
});

Custom Console (React Native, Electron)

logger.configure({
  level: "none",
  callbackIgnoresLevel: true,
  callback: (level, context, message, ...args) => {
    NativeModules.Logger[level](`[${context}] ${message}`, args);
  },
});

Types

import type {
  LogLevel,          // "log" | "warn" | "error"
  LogLevelConfig,    // "all" | "warn-error" | "error-only" | "none"
  LogCallback,       // (level, context, message, ...args) => void
  LoggerConfig,      // { level, callback?, callbackIgnoresLevel? }
} from "@real-router/logger";

Related Packages

| Package | Description | |---------|-------------| | @real-router/core | Core router (uses logger internally) | | @real-router/logger-plugin | Transition logging plugin (uses logger internally) |

Contributing

See contributing guidelines for development setup and PR process.

License

MIT © Oleg Ivanov