locutus/esm/php/array/array_is_list.js

Locutus other languages' standard libraries to JavaScript for fun and educational purposes

import { normalizeArrayKey } from "../_helpers/_phpTypes.js";
export function array_is_list(input) {
    //      discuss at: https://locutus.io/php/array_is_list/
    // parity verified: PHP 8.3
    //     original by: Kevin van Zonneveld (https://kvz.io)
    //          note 1: Plain JS objects cannot preserve PHP insertion order for integer-like associative keys.
    //                  Use real JS arrays when numeric key order matters for PHP-style list detection.
    //       example 1: array_is_list(['a', 'b', 'c'])
    //       returns 1: true
    //       example 2: array_is_list({'0': 'a', '2': 'b'})
    //       returns 2: false
    //       example 3: array_is_list({})
    //       returns 3: true
    // Integer-like keys on plain JS objects are always enumerated numerically by the language runtime,
    // so PHP insertion-order semantics for associative numeric keys can only be preserved with real arrays.
    const keys = Object.keys(input);
    for (let i = 0; i < keys.length; i++) {
        if (normalizeArrayKey(keys[i] ?? '') !== i) {
            return false;
        }
    }
    return true;
}