| // @flow strict |
| |
| import { SYMBOL_ITERATOR } from '../polyfills/symbols'; |
| |
| /** |
| * Returns true if the provided object is an Object (i.e. not a string literal) |
| * and is either Iterable or Array-like. |
| * |
| * This may be used in place of [Array.isArray()][isArray] to determine if an |
| * object should be iterated-over. It always excludes string literals and |
| * includes Arrays (regardless of if it is Iterable). It also includes other |
| * Array-like objects such as NodeList, TypedArray, and Buffer. |
| * |
| * @example |
| * |
| * isCollection([ 1, 2, 3 ]) // true |
| * isCollection('ABC') // false |
| * isCollection({ length: 1, 0: 'Alpha' }) // true |
| * isCollection({ key: 'value' }) // false |
| * isCollection(new Map()) // true |
| * |
| * @param obj |
| * An Object value which might implement the Iterable or Array-like protocols. |
| * @return {boolean} true if Iterable or Array-like Object. |
| */ |
| export default function isCollection(obj: mixed): boolean { |
| if (obj == null || typeof obj !== 'object') { |
| return false; |
| } |
| |
| // Is Array like? |
| const length = obj.length; |
| if (typeof length === 'number' && length >= 0 && length % 1 === 0) { |
| return true; |
| } |
| |
| // Is Iterable? |
| return typeof obj[SYMBOL_ITERATOR] === 'function'; |
| } |