@bisham/predicates

A utility class providing type-safe predicate functions for common value checks.

Installation

``bash
npm install @bisham/predicates
`

Usage

`typescript
import { Predicates } from '@bisham/predicates';

// Type-safe checks
if (Predicates.isString(value)) {
// TypeScript knows value is string here
console.log(value.toUpperCase());
}
`

Available Methods

| Method | Signature | Description |
|--------|-----------|-------------|
| Type Checks |
| isString | (value: unknown): value is string | Checks if value is a string |
| isEmptyString | (value: unknown): value is "" | Checks if value is an empty string |
| isNotEmptyString | (value: unknown): value is string | Checks if value is a non-empty string |
| isNumber | (value: unknown): value is number | Checks if value is a number |
| isBoolean | (value: unknown): value is boolean | Checks if value is a boolean |
| isFunction | (func: unknown): func is Function | Checks if value is a function |
| isObject | (value: unknown): value is Record | Checks if value is an object (not null) |
| isDate | (value: unknown): value is Date | Checks if value is a Date instance |
| Null/Undefined Checks |
| isNull | (value: unknown): value is null | Checks if value is null |
| isUndefined | (value: unknown): value is undefined | Checks if value is undefined |
| isEmpty | (value: unknown): value is null \| undefined | Checks if value is null or undefined |
| isNotEmpty | (value: unknown): value is {} | Checks if value is neither null nor undefined |
| Array Checks |
| isEmptyArray | (value: unknown): value is [] | Checks if value is an empty array |
| isNotEmptyArray | (value: unknown): value is Array | Checks if value is a non-empty array |
| Object Checks |
| isEmptyObject | (value: unknown): value is Record | Checks if value is an object with no properties |
| Date Checks |
| isValidDateString | (value: unknown): value is string | Checks if value is a valid date string |
| Environment Checks |
| isBrowser | (): boolean | Checks if current environment is a browser |
| isOnline | (): boolean | Returns online status (browser) or false (Node.js) |

Examples

`typescript
import { Predicates } from '@bisham/predicates';

// Type guards with TypeScript narrowing
const value: unknown = "hello";

if (Predicates.isString(value)) {
// TypeScript knows value is string
console.log(value.length); // ✅ Works
}

// Check for empty values
if (Predicates.isEmpty(userInput)) {
console.log("Input is required");
}

// Check arrays
if (Predicates.isNotEmptyArray(items)) {
// TypeScript knows items is Array
items.forEach(item => console.log(item));
}

// Environment checks
if (Predicates.isBrowser()) {
console.log("Running in browser");
}

if (Predicates.isOnline()) {
console.log("User is online");
}
``