tessl/npm-xe-utils

Comprehensive JavaScript utility library with 150+ functions for objects, arrays, dates, strings, numbers, and more

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Type Checking & Validation

Name: tessl/npm-xe-utils
Author: tessl

Comprehensive type checking utilities for runtime validation and type guards. Includes checks for all JavaScript primitive types, built-in objects, DOM elements, and web API types. Essential for robust error handling and input validation.

Capabilities

Primitive Type Checks

Type checking functions for JavaScript primitive types with TypeScript type guards.

/**
 * Check if value is an array
 * @param val - Value to check
 * @returns True if value is array
 */
function isArray(val: any): val is any[];

/**
 * Check if value is a string
 * @param val - Value to check
 * @returns True if value is string
 */
function isString(val: any): val is string;

/**
 * Check if value is a number (excluding NaN)
 * @param val - Value to check
 * @returns True if value is number
 */
function isNumber(val: any): val is number;

/**
 * Check if value is a boolean
 * @param val - Value to check
 * @returns True if value is boolean
 */
function isBoolean(val: any): val is boolean;

/**
 * Check if value is a function
 * @param val - Value to check
 * @returns True if value is function
 */
function isFunction(val: any): val is Function;

/**
 * Check if value is a symbol
 * @param val - Value to check
 * @returns True if value is symbol
 */
function isSymbol(val: any): val is symbol;

Object Type Checks

Type checking for various object types and complex structures.

/**
 * Check if value is an object (excluding null and arrays)
 * @param val - Value to check
 * @returns True if value is object
 */
function isObject(val: any): val is object;

/**
 * Check if value is a plain object (created by {} or new Object())
 * @param val - Value to check
 * @returns True if value is plain object
 */
function isPlainObject(val: any): val is object;

/**
 * Check if value is a Date object
 * @param val - Value to check
 * @returns True if value is Date
 */
function isDate(val: any): val is Date;

/**
 * Check if value is a RegExp object
 * @param val - Value to check
 * @returns True if value is RegExp
 */
function isRegExp(val: any): val is RegExp;

/**
 * Check if value is an Error object
 * @param val - Value to check
 * @returns True if value is Error
 */
function isError(val: any): val is Error;

/**
 * Check if value is a TypeError object
 * @param val - Value to check
 * @returns True if value is TypeError
 */
function isTypeError(val: any): val is TypeError;

Collection Type Checks

Type checking for ES6+ collection types.

/**
 * Check if value is a Map object
 * @param val - Value to check
 * @returns True if value is Map
 */
function isMap(val: any): val is Map<any, any>;

/**
 * Check if value is a WeakMap object
 * @param val - Value to check
 * @returns True if value is WeakMap
 */
function isWeakMap(val: any): val is WeakMap<any, any>;

/**
 * Check if value is a Set object
 * @param val - Value to check
 * @returns True if value is Set
 */
function isSet(val: any): val is Set<any>;

/**
 * Check if value is a WeakSet object
 * @param val - Value to check
 * @returns True if value is WeakSet
 */
function isWeakSet(val: any): val is WeakSet<any>;

Null/Undefined Checks

Specialized checks for null, undefined, and related states.

/**
 * Check if value is null
 * @param val - Value to check
 * @returns True if value is null
 */
function isNull(val: any): val is null;

/**
 * Check if value is undefined
 * @param val - Value to check
 * @returns True if value is undefined
 */
function isUndefined(val: any): val is undefined;

/**
 * Check if value is NaN
 * @param val - Value to check
 * @returns True if value is NaN
 */
function isNaN(val: any): boolean;

/**
 * Check if value is null or undefined
 * @param val1 - First value
 * @param val2 - Second value (optional)
 * @returns True if both values are null/undefined or equal
 */
function eqNull(val1: any, val2?: any): boolean;

Number Type Checks

Specialized number type checking including finite, integer, and float checks.

/**
 * Check if value is a finite number
 * @param val - Value to check
 * @returns True if value is finite number
 */
function isFinite(val: any): boolean;

/**
 * Check if value is an integer
 * @param val - Value to check
 * @returns True if value is integer
 */
function isInteger(val: any): boolean;

/**
 * Check if value is a float (non-integer number)
 * @param val - Value to check
 * @returns True if value is float
 */
function isFloat(val: any): boolean;

DOM & Web API Checks

Type checking for browser and DOM-related objects.

/**
 * Check if value is a DOM element
 * @param val - Value to check
 * @returns True if value is DOM element
 */
function isElement(val: any): val is Element;

/**
 * Check if value is a Document object
 * @param val - Value to check
 * @returns True if value is Document
 */
function isDocument(val: any): val is Document;

/**
 * Check if value is a Window object
 * @param val - Value to check
 * @returns True if value is Window
 */
function isWindow(val: any): val is Window;

/**
 * Check if value is a FormData object
 * @param val - Value to check
 * @returns True if value is FormData
 */
function isFormData(val: any): val is FormData;

/**
 * Check if value is an Arguments object
 * @param val - Value to check
 * @returns True if value is Arguments
 */
function isArguments(val: any): val is IArguments;

Value State Checks

Utilities for checking value states and emptiness.

/**
 * Check if value is empty (null, undefined, empty string, empty array, empty object)
 * @param val - Value to check
 * @returns True if value is considered empty
 */
function isEmpty(val: any): boolean;

/**
 * Check if date is a leap year
 * @param date - Date to check
 * @returns True if year is leap year
 */
function isLeapYear(date: Date | number): boolean;

/**
 * Check if date is valid
 * @param date - Date to validate
 * @returns True if date is valid
 */
function isValidDate(date: any): boolean;

Deep Comparison

Advanced comparison utilities for deep equality checking.

/**
 * Deep equality comparison
 * @param val1 - First value
 * @param val2 - Second value
 * @returns True if values are deeply equal
 */
function isEqual(val1: any, val2: any): boolean;

/**
 * Deep equality comparison with custom comparator
 * @param val1 - First value
 * @param val2 - Second value
 * @param callback - Custom comparison function
 * @returns True if values are equal according to callback
 */
function isEqualWith(
  val1: any, 
  val2: any, 
  callback: (value1: any, value2: any, key?: string) => boolean | undefined
): boolean;

/**
 * Check if object matches source properties
 * @param obj - Object to check
 * @param source - Source object with properties to match
 * @returns True if object contains all source properties with same values
 */
function isMatch(obj: any, source: any): boolean;

Type Information

Utilities for getting detailed type information.

/**
 * Get detailed type of value
 * @param val - Value to analyze
 * @returns Detailed type string
 */
function getType(val: any): string;

Usage Examples:

import { 
  isArray, isString, isNumber, isObject, isEmpty, 
  isEqual, isValidDate, getType 
} from 'xe-utils';

// Basic type checking
const data = ['hello', 42, { name: 'Alice' }, null];

data.forEach(item => {
  if (isString(item)) {
    console.log(`String: ${item.toUpperCase()}`);
  } else if (isNumber(item)) {
    console.log(`Number: ${item * 2}`);
  } else if (isObject(item)) {
    console.log(`Object:`, item);
  }
});

// Validation
function validateUser(user) {
  if (isEmpty(user)) {
    throw new Error('User data is required');
  }
  
  if (!isString(user.name) || isEmpty(user.name)) {
    throw new Error('Valid name is required');
  }
  
  if (!isNumber(user.age) || user.age < 0) {
    throw new Error('Valid age is required');
  }
  
  return true;
}

// Deep comparison
const obj1 = { user: { name: 'Alice', preferences: { theme: 'dark' } } };
const obj2 = { user: { name: 'Alice', preferences: { theme: 'dark' } } };

console.log(isEqual(obj1, obj2)); // true

// Type information
console.log(getType([])); // 'Array'
console.log(getType(new Date())); // 'Date'
console.log(getType(/regex/)); // 'RegExp'

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