@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