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# is.js
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is.js is a comprehensive micro check library for JavaScript that provides type checking and validation operations across different JavaScript environments. It offers a wide range of utility functions for checking data types, values, and conditions with support for AMD, Node.js, and browser environments through a universal module definition pattern.
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## Package Information
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- **Package Name**: is_js
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- **Package Type**: npm
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- **Language**: JavaScript
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- **Installation**: `npm install is_js`
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## Core Imports
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```javascript
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const is = require('is_js');
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```
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For AMD:
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```javascript
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define(['is_js'], function(is) {
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  // Use is object
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});
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```
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For browsers (global):
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```html
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<script src="is.js"></script>
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<script>
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  // is is available globally
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</script>
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```
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## Basic Usage
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```javascript
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const is = require('is_js');
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// Basic type checking
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console.log(is.string('hello'));     // true
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console.log(is.number(42));          // true
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console.log(is.array([1, 2, 3]));    // true
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// Using modifiers
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console.log(is.not.string(123));     // true
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console.log(is.all.number(1, 2, 3)); // true
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console.log(is.any.string('a', 123)); // true
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// Complex validation
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console.log(is.email('test@example.com')); // true
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console.log(is.url('https://example.com')); // true
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console.log(is.even(4));             // true
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```
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## Architecture
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is.js is built around several key components:
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- **Core Interface**: Main `is` object containing all checking functions
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- **Modifier System**: `not`, `all`, and `any` interfaces providing function variants
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- **Universal Module**: UMD pattern supporting AMD, CommonJS, and browser globals
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- **Fluent API**: Consistent boolean return values across all checking functions
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- **Environment Detection**: Browser and device-specific checks available in browser contexts
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## Capabilities
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### Type Checking
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Core type validation functions for JavaScript primitives and objects. Essential for runtime type safety and input validation.
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```javascript { .api }
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// Basic type checks
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function arguments(value: any): boolean;
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function array(value: any): boolean;
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function boolean(value: any): boolean;
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function date(value: any): boolean;
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function error(value: any): boolean;
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function function(value: any): boolean;
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function number(value: any): boolean;
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function object(value: any): boolean;
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function regexp(value: any): boolean;
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function string(value: any): boolean;
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// Special type checks
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function char(value: any): boolean;
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function domNode(value: any): boolean;
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function json(value: any): boolean;
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function nan(value: any): boolean;
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function null(value: any): boolean;
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function sameType(value: any, other: any): boolean;
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function undefined(value: any): boolean;
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function windowObject(value: any): boolean;
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```
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[Type Checking](./type-checking.md)
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### Value Presence and State
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Functions for checking value existence, truthiness, and basic state validation.
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```javascript { .api }
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function empty(value: any): boolean;
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function existy(value: any): boolean;
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function falsy(value: any): boolean;
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function truthy(value: any): boolean;
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function space(value: any): boolean;
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```
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[Presence Checking](./presence-checking.md)
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### String Validation
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String-specific validation including case checking, content analysis, and format validation.
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```javascript { .api }
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function capitalized(value: string): boolean;
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function endWith(string: string, target: string): boolean;
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function include(string: string, target: string): boolean;
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function lowerCase(value: string): boolean;
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function palindrome(value: string): boolean;
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function startWith(string: string, target: string): boolean;
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function upperCase(value: string): boolean;
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```
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[String Checking](./string-checking.md)
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### Pattern Matching
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Regular expression-based validation for common data formats including emails, URLs, phone numbers, and postal codes.
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```javascript { .api }
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function affirmative(value: any): boolean;
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function alphaNumeric(value: any): boolean;
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function caPostalCode(value: any): boolean;
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function creditCard(value: any): boolean;
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function dateString(value: any): boolean;
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function email(value: any): boolean;
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function hexadecimal(value: any): boolean;
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function hexColor(value: any): boolean;
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function ip(value: any): boolean;
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function ipv4(value: any): boolean;
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function ipv6(value: any): boolean;
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function nanpPhone(value: any): boolean;
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function socialSecurityNumber(value: any): boolean;
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function timeString(value: any): boolean;
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function ukPostCode(value: any): boolean;
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function url(value: any): boolean;
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function usZipCode(value: any): boolean;
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```
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[Pattern Matching](./pattern-matching.md)
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### Numeric Operations
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Mathematical validation functions for number properties, comparisons, and arithmetic checks.
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```javascript { .api }
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function above(n: number, min: number): boolean;
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function decimal(n: number): boolean;
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function equal(value: any, other: any): boolean;
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function even(n: number): boolean;
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function finite(n: number): boolean;
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function infinite(n: number): boolean;
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function integer(n: number): boolean;
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function negative(n: number): boolean;
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function odd(n: number): boolean;
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function positive(n: number): boolean;
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function under(n: number, max: number): boolean;
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function within(n: number, min: number, max: number): boolean;
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```
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[Numeric Operations](./numeric-operations.md)
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### Collection Validation
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Functions for validating arrays, objects, and their properties.
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```javascript { .api }
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function inArray(value: any, array: any[]): boolean;
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function sorted(array: any[], sign?: string): boolean;
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function propertyCount(object: any, count: number): boolean;
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function propertyDefined(object: any, property: string): boolean;
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```
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[Collection Validation](./collection-validation.md)
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### Date and Time
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Comprehensive date validation including relative time checks, specific date matching, and time range validation.
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```javascript { .api }
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function day(date: Date, day: string): boolean;
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function dayLightSavingTime(date: Date): boolean;
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function future(date: Date): boolean;
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function inDateRange(date: Date, start: Date, end: Date): boolean;
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function leapYear(year: number): boolean;
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function month(date: Date, month: string): boolean;
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function past(date: Date): boolean;
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function quarterOfYear(date: Date, quarter: number): boolean;
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function today(date: Date): boolean;
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function tomorrow(date: Date): boolean;
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function weekend(date: Date): boolean;
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function weekday(date: Date): boolean;
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function year(date: Date, year: number): boolean;
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function yesterday(date: Date): boolean;
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```
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[Date and Time](./date-time.md)
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### Environment Detection
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Browser and device detection functions for responsive behavior and feature detection.
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```javascript { .api }
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// Browser detection
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function chrome(range?: string | number): boolean;
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function edge(range?: string | number): boolean;
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function firefox(range?: string | number): boolean;
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function ie(range?: string | number): boolean;
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function opera(range?: string | number): boolean;
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function safari(range?: string | number): boolean;
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// Device detection
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function android(): boolean;
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function ios(): boolean;
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function mobile(): boolean;
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function tablet(): boolean;
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function desktop(): boolean;
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// Operating system detection
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function linux(): boolean;
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function mac(): boolean;
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function windows(): boolean;
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```
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[Environment Detection](./environment-detection.md)
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### Configuration and Utilities
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Library configuration and utility functions for customization and namespace management.
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```javascript { .api }
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function setNamespace(): typeof is;
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function setRegexp(regexp: RegExp, name: string): void;
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```
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[Configuration](./configuration.md)
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## Interface Modifiers
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### not Interface
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All functions are available with negated logic through the `not` interface:
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```javascript { .api }
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interface NotInterface {
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  [K in keyof IsInterface]: IsInterface[K];
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}
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const not: NotInterface;
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```
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### all Interface
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Functions supporting the `all` interface check that all provided arguments pass the test:
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```javascript { .api }
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interface AllInterface {
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  [K in SupportedFunction]: (...args: any[]) => boolean;
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}
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const all: AllInterface;
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```
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### any Interface
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Functions supporting the `any` interface check that at least one provided argument passes the test:
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```javascript { .api }
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interface AnyInterface {
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  [K in SupportedFunction]: (...args: any[]) => boolean;
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}
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const any: AnyInterface;
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```
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## Types
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```javascript { .api }
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interface IsInterface {
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  VERSION: string; // '0.8.0' as defined in source code
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  not: NotInterface;
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  all: AllInterface;
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  any: AnyInterface;
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  // All checking functions return boolean
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  [functionName: string]: (...args: any[]) => boolean;
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}
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// Main export
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const is: IsInterface;
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```