locutus/esm/php/array/array_key_first.js

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

import { normalizeArrayKey } from "../_helpers/_phpTypes.js";
export function array_key_first(input) {
    //      discuss at: https://locutus.io/php/array_key_first/
    // parity verified: PHP 8.3
    //     original by: Kevin van Zonneveld (https://kvz.io)
    //       example 1: array_key_first({ a: 1, b: 2 })
    //       returns 1: 'a'
    //       example 2: array_key_first(['x', 'y'])
    //       returns 2: 0
    //       example 3: array_key_first([])
    //       returns 3: null
    const [firstKey] = Object.keys(input);
    return typeof firstKey === 'string' ? normalizeArrayKey(firstKey) : null;
}