expo-modules-core/src/sweet/setUpJsLogger.fx.ts

The core of Expo Modules architecture

import { CodedError } from '../errors/CodedError';
import { requireOptionalNativeModule } from '../requireNativeModule';

type LogListener = {
  action: (...data: any[]) => void;
  eventName: string;
};

if (
  __DEV__ &&
  typeof window !== 'undefined' &&
  (process.env.EXPO_OS === 'android' || process.env.EXPO_OS === 'ios')
) {
  const NativeJSLogger = requireOptionalNativeModule('ExpoModulesCoreJSLogger');
  if (NativeJSLogger) {
    const onNewException: LogListener = {
      eventName: 'ExpoModulesCoreJSLogger.onNewError',
      action: console.error,
    };

    const onNewWarning: LogListener = {
      eventName: 'ExpoModulesCoreJSLogger.onNewWarning',
      action: console.warn,
    };

    const onNewDebug: LogListener = {
      eventName: 'ExpoModulesCoreJSLogger.onNewDebug',
      action: console.debug,
    };

    const onNewInfo: LogListener = {
      eventName: 'ExpoModulesCoreJSLogger.onNewInfo',
      action: console.info,
    };

    const onNewTrace: LogListener = {
      eventName: 'ExpoModulesCoreJSLogger.onNewTrace',
      action: console.trace,
    };

    const listeners: LogListener[] = [
      onNewException,
      onNewWarning,
      onNewDebug,
      onNewInfo,
      onNewTrace,
    ];

    for (const listener of listeners) {
      NativeJSLogger.addListener(listener.eventName, ({ message }: { message: string }) => {
        listener.action(message);
      });
    }
  }
}

declare namespace globalThis {
  let ExpoModulesCore_CodedError: undefined | typeof CodedError;
}

// We have to export `CodedError` via global object to use in later in the C++ code.
globalThis.ExpoModulesCore_CodedError = CodedError;