or-empty-array

A lightweight, strongly typed RxJS pipeable operator that converts null or undefined values (for example HTTP 204 No Content responses or streams with empty values) into an empty array []. If the emitted value is already an array, it is returned unchanged.

Installation

npm install or-empty-array

Note: requires rxjs (>= 7.0.0).

Usage

import { of } from 'rxjs';
import { orEmptyArray } from 'or-empty-array';

// Handling null responses -> []
of<string[] | null>(null)
  .pipe(orEmptyArray())
  .subscribe((items) => {
    console.log(items); // []
  });

// Handling undefined responses -> []
of<number[] | undefined>(undefined)
  .pipe(orEmptyArray())
  .subscribe((items) => {
    console.log(items); // []
  });

// Leaves existing arrays unchanged
of(['item1', 'item2'])
  .pipe(orEmptyArray())
  .subscribe((items) => {
    console.log(items); // ['item1', 'item2']
  });

Angular / HTTP Client example

import { HttpClient } from '@angular/common/http';
import { inject, Injectable } from '@angular/core';
import { orEmptyArray } from 'or-empty-array';
import { Observable } from 'rxjs';

@Injectable({ providedIn: 'root' })
export class ItemsService {
  private http = inject(HttpClient);

  getItems(): Observable<Item[]> {
    return this.http.get<Item[] | null>('/api/items').pipe(
      orEmptyArray()
    );
  }
}

Build & Test

# Build
npx nx build or-empty-array

# Test
npx nx test or-empty-array