@dloizides/utils
Type-safe utility functions for TypeScript projects
Installation
npm install @dloizides/utils
# or
yarn add @dloizides/utils
# or
pnpm add @dloizides/utils
Features
- Type Guards:
isValueDefined,isNotEmptyArray,isNotEmptyString,isNullOrUndefined,isEmptyArray,isEmptyString - Assertions:
assertDefined - Zero Dependencies: No runtime dependencies
- Tree-shakeable: Only import what you need
- TypeScript First: Full type inference and narrowing
Usage
Type Guards
import { isValueDefined, isNotEmptyArray, isNotEmptyString } from '@dloizides/utils';
// isValueDefined - Check if value is not null or undefined
const user = getUserOrNull();
if (isValueDefined(user)) {
console.log(user.name); // TypeScript knows user is defined
}
// isNotEmptyArray - Check if array has elements
const items = getItems();
if (isNotEmptyArray(items)) {
console.log(items[0]); // Safe to access first element
}
// isNotEmptyString - Check if string has content
const input = formData.get('name');
if (isNotEmptyString(input)) {
saveUser(input); // String is guaranteed to have content
}
Assertions
import { assertDefined } from '@dloizides/utils';
function processUser(user: User | null) {
assertDefined(user, 'User is required');
// user is now narrowed to User
return user.name.toUpperCase();
}
Subpath Imports
// Import only guards
import { isValueDefined } from '@dloizides/utils/guards';
// Import only assertions
import { assertDefined } from '@dloizides/utils/assertions';
API Reference
Type Guards
| Function | Description |
|---|---|
isValueDefined<T>(value) | Returns true if value is not null or undefined |
isNotEmptyArray<T>(value) | Returns true if value is an array with length > 0 |
isNotEmptyString(value) | Returns true if value is a non-empty string (after trim) |
isNullOrUndefined(value) | Returns true if value is null or undefined |
isEmptyArray(value) | Returns true if value is an empty array |
isEmptyString(value) | Returns true if value is empty or whitespace only |
Assertions
| Function | Description |
|---|---|
assertDefined<T>(value, message?) | Throws if value is null or undefined |
License
MIT