AppStateEnhancer

File: application-state.enhancer.ts

Overview

The ApplicationStateEnhancer class enriches standard JavaScript Error objects by providing a snapshot of the application's current state, such as environment variables, configurations, and package dependencies. This class is part of the error-enhanced library, aiming to aid in debugging and system monitoring.

Properties

Property	Description
_environment	Holds the current environment (e.g., "production", "development"). Defaults to an empty string.
_nodeVersion	The version of Node.js currently in use. Defaults to an empty string.
_configurations	Application configurations that could affect behavior.
_envVars	Environment variables at the time of instantiation.
_stateSnapshot	A snapshot of the application state at a given time.
_eventHistory	A limited history of events added to the instance.
_dependencies	Current package dependencies.
_dependenciesCache	Cached package dependencies.
_packageManagerCache	Cache to store the availability of package managers ('npm', 'yarn', etc.).
_lastFetchTime	The last time dependencies were fetched.

Methods

Public Methods

setConfigurations(configs: Record<string, any>): this

Sets the application configurations.

Usage Example:

const errorInfo = new ApplicationStateEnhancer();
errorInfo.setConfigurations({ apiEndpoint: "https://api.example.com" });

setStateSnapshot(snapshot: Record<string, any>): this

Sets a snapshot of the application state, which can include any critical variables or settings that you might need for debugging or system monitoring.

Recommendations:

• It's useful to call this method before making any significant state changes in your application or right before error-prone operations.

• Consider including information like user IDs, session tokens, or any other state variables that would provide context in case of an error.

Usage Example:

const snapshot = {
  userID: '12345',
  sessionToken: 'abcde',
};
errorInfo.setStateSnapshot(snapshot);

addToEventHistory(event: string): this

Adds an event to the event history. The history is limited to the last 10 events for memory efficiency.

Recommendations:

• Use this method to log significant user actions or system events that lead up to an error or other important system state.

• You may want to add a timestamp to each event for more detailed tracking.

Usage Example:

errorInfo.addToEventHistory('User logged in');
errorInfo.addToEventHistory('User clicked on button X');

setEnvironment(environment: Environment): this

Sets the current environment of the application. It utilizes an enum to ensure strong typing and consistency across different parts of the application.

Recommendations:

• Always use the Environment enum to set the environment to ensure data consistency.

• You should update this setting whenever your application transitions between different environments to ensure accurate logging and debugging.

Usage Example:

errorInfo.setEnvironment(Environment.PRODUCTION);

Private Methods

• _fetchDependencies(): any: Fetches the dependencies from the package manager.

• _isPackageManagerInstalled(name: string): boolean: Checks if a package manager is installed, with caching.

• _handleAppStateError(e: Error, context: string): Handles application state errors.

Getters

• configurations

• envVars

• stateSnapshot

• eventHistory

• dependencies

• environment

• nodeVersion

Common Use-Cases

• Debugging: Provides rich contextual information useful for debugging.

• System Monitoring: Helps in keeping track of system state for monitoring tools.

• Audit Logging: Useful for detailed logging of system state during errors.

---