npm package: @homeofthings/node-utils
Description: HomeOfThings - Node Utils: various utilities and common types
Author: Guenter Sandner
Latest version: 1.0.5

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# @homeofthings/node-utils

- `AsyncContext<T>`: little wrapper around `AsyncLocalStorage` providing default value

  ```Typescript
  asyncContext = new AsyncContext(defaultContext);
  ...
  asyncContext.set(newContext)
  ...
  currentContext = asyncContext.get();
  ```

- `ConfigService`: singleton service based on node-config

```Typescript
configService = new ConfigService({ configDirectory: 'path/to/config' });
```

then use one of the methods provided by the `ConfigService`:

```TypeScript
export declare class ConfigService {
  readonly configDirectory: string;
  readonly environment: string;

  constructor(_opts: ConfigOptions);

  getConfig(key: string): object | undefined;
  reloadConfig(): void;

  getString(key: string, defaultValue: string): string;
  getNumber(key: string, defaultValue: number): number;
  getBoolean(key: string, defaultValue: boolean): boolean;
  getObject(key: string, defaultValue: object): object;

  // resolve path relative to config-directory
  getPath(key: string, defaultValue: string): string;

  getOptionalString(key: string): string | undefined;
  getOptionalNumber(key: string): number | undefined;
  getOptionalBoolean(key: string): boolean | undefined;
  getOptionalObject(key: string): object | undefined;

  // resolve path relative to config-directory
  getOptionalPath(key: string): string | undefined;
}
```

reload on SIGHUP:

```TypeScript
process.on('SIGHUP', () => ConfigService.getInstance().reloadConfig());
```

- `LruCache<T>`: LRU cache

  ```Typescript
  cache = new LruCache<UserSession, number>(SESSION_CACHE_SIZE);

  cache.set(id, userSession); // add this to the cache and mark it as least recently used
  ...
  cache.get(anotherId); // if it is available in the cache it will be marked as least recently used
  ```

- `sequentialize`: run `Promises` in sequence

  ```Typescript
  await sequentialize(item.map(() => doWork(item)));
  ```

- `wait`: wait until a condition is true or timed out

  ```Typescript
  await wait(condition); // polls until condition is true
  await wait(condition, 1000); // polls until condition is true or timed out after 1000ms
  ```

- `WritableStrings`: a `Writable` for writing to a string array

- `quoteArgs` and `quoteArg`: quote arguments for better readability (e.g. for logging)