is-array-of

A lightweight JavaScript library to validate that all elements in an array are of a specific type.

Installation

npm install is-array-of

Usage

const isArrayOf = require('is-array-of');

// Validate primitive types using strings
isArrayOf([1, 2, 3], 'number');        // true
isArrayOf(['a', 'b', 'c'], 'string');  // true
isArrayOf([true, false], 'boolean');   // true
isArrayOf([1, '2', 3], 'number');      // false

// Validate arrays
isArrayOf([[1], [2], [3]], 'array');   // true

// Validate objects
isArrayOf([{}, {a: 1}], 'object');     // true

// Validate using constructor functions
class Person {
  constructor(name) {
    this.name = name;
  }
}

const people = [new Person('John'), new Person('Jane')];
isArrayOf(people, Person);             // true

// Built-in constructors
isArrayOf([new Date(), new Date()], Date);  // true
isArrayOf([/test/, /regex/], RegExp);       // true

// Empty arrays return true
isArrayOf([], 'string');               // true

// Non-arrays return false
isArrayOf('not an array', 'string');   // false
isArrayOf(null, 'string');             // false

API

isArrayOf(arr, type)

Parameters

• arr (Array): The array to validate
• type (string | Function): The type to check against
  • String values: 'string', 'number', 'boolean', 'function', 'object', 'array', 'null', 'undefined'
  • Constructor functions: Any constructor function (e.g., Date, RegExp, custom classes)

Returns

• boolean: Returns true if all elements match the specified type, false otherwise

Features

• ✅ Supports primitive type validation (string, number, boolean, etc.)
• ✅ Supports constructor function validation (Date, RegExp, custom classes)
• ✅ Handles edge cases (empty arrays, null, undefined)
• ✅ Zero dependencies
• ✅ TypeScript definitions included
• ✅ Lightweight and fast

License

MIT