react-native-firebase/lib/modules/crash/index.js

// @flow
import { NativeModules } from 'react-native';
import { Base } from './../base';

const FirebaseCrash = NativeModules.RNFirebaseCrash;

export default class Analytics extends Base {
  /**
   * Logs a message that will appear in a subsequent crash report.
   * @param {string} message
   * @param params
   */
  log(message: string): void {
    FirebaseCrash.log(message);
  }

  /**
   * Logs a message that will appear in a subsequent crash report as well as in logcat.
   * NOTE: Android only functionality. iOS will just log the message.
   * @param {string} message
   * @param {number} level
   * @param {string} tag
   */
  logcat(level: number, tag: string, message: string): void {
    FirebaseCrash.logcat(level, tag, message);
  }

  /**
   * Generates a crash report for the given message. This method should be used for unexpected
   * exceptions where recovery is not possible.
   * NOTE: on iOS, this will cause the app to crash as it's the only way to ensure the exception
   * gets sent to Firebase.  Otherwise it just gets lost as a log message.
   * @param {Error} error
   * @param maxStackSize
   */
  report(error: Error, maxStackSize: Number = 10): void {
    if (!error || !error.code || !error.message) return;

    let errorMessage = `Message: ${error.message}\r\n`;

    if (error.code) {
      errorMessage = `${errorMessage}Code: ${error.code}\r\n`;
    }

    const stackRows = error.stack.split('\n');
    errorMessage = `${errorMessage}\r\nStack: \r\n`;
    for (let i = 0, len = stackRows.length; i < len; i++) {
      if (i === maxStackSize) break;
      errorMessage = `${errorMessage}  -  ${stackRows[i]}\r\n`;
    }

    FirebaseCrash.report(errorMessage);
  }

  get namespace(): string {
    return 'firebase:crash';
  }
}