Merge pull request #1 from ewerk/feature/has-empty-value

Feature/has empty value

.github/workflows/pr-verify.yml

@@ -0,0 +1,18 @@
+name: PR Verification
+
+on:
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+      - run: npm ci
+      - run: npm run lint
+      - run: npm test

README.md

@@ -57,6 +57,25 @@ const titleNew$: string = value$.pipe(
 );
 ```
 
+### `hasEmptyValue`
+
+This function checks if a value is considered "empty". A value is considered empty if it is an empty array, `null`, `undefined`, or an empty string.
+This function could be useful for validating user input.
+
+```typescript
+import { hasEmptyValue } from '@ewerk/null-or-undefined';
+
+console.log(hasEmptyValue('')); // true
+console.log(hasEmptyValue([])); // true
+console.log(hasEmptyValue(null)); // true
+console.log(hasEmptyValue(undefined)); // true
+
+console.log(hasEmptyValue(false)); // false
+console.log(hasEmptyValue(0)); // false
+console.log(hasEmptyValue('test string')); // false
+console.log(hasEmptyValue(['test', 'string'])); // false
+```
+
 ## Contributing
 
 Contributions are welcome! Please open an issue or submit a pull request on GitHub.

src/has-empty-value/has-empty-value.spec.ts

@@ -0,0 +1,20 @@
+import { hasEmptyValue } from './has-empty-value';
+
+describe('hasEmptyValue helper', () => {
+  it('should return true, if "empty" value was provided', () => {
+    expect(hasEmptyValue('')).toBe(true);
+    expect(hasEmptyValue([])).toBe(true);
+    expect(hasEmptyValue(null as unknown as string)).toBe(true);
+    expect(hasEmptyValue(undefined as unknown as string)).toBe(true);
+  });
+
+  it('should return false, if "non-empty" value was provided', () => {
+    expect(hasEmptyValue(false)).toBe(false);
+    expect(hasEmptyValue(0)).toBe(false);
+    expect(hasEmptyValue('test string')).toBe(false);
+    expect(hasEmptyValue([
+      'test',
+      'string',
+    ])).toBe(false);
+  });
+});

src/has-empty-value/has-empty-value.ts

@@ -0,0 +1,8 @@
+import { isNullOrUndefined } from '../is-null-or-undefined/is-null-or-undefined';
+
+export const hasEmptyValue = (val: number | string | boolean | Array<any>): boolean => {
+  if (val instanceof Array) {
+    return val.length === 0;
+  }
+  return isNullOrUndefined(val) || val === '' ;
+};