Type safe utility functions for checking nullish values. It's dependency free and has no dependencies on external libraries.
You can install this package using npm:
npm install @ewerk/null-or-undefinedThis function checks if a value is either null or undefined.
import { isNullOrUndefined } from '@ewerk/null-or-undefined';
const value = null;
if (isNullOrUndefined(value)) {
console.log('Value is null or undefined');
}This function checks if a value is neither null nor undefined. A neat use case is to filter out null and undefined values in RxJS observables.
import { neitherNullNorUndefined } from '@ewerk/null-or-undefined';
const value = 'Hello';
if (neitherNullNorUndefined(value)) {
console.log('Value is neither null nor undefined');
}
// Example with RxJS
const value$: Observable<{title: string} | undefined> = of(undefined);
// before
const titleOld$: string = value$.pipe(
filter((value) => value !== null && value !== undefined),
map((value) => value as {title: string}), // cast is necessary to get rid of the undefined type
map((value) => value.title),
);
// after
const titleNew$: string = value$.pipe(
filter(neitherNullNorUndefined),
map((value) => value.title)
);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.
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'])); // falseContributions are welcome! Please open an issue or submit a pull request on GitHub.
This project is licensed under the MIT License.
Florian Symanowski (@iceteabottle)