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getKeys

Extracts keys from arrays, objects, and other values with enhanced type safety. Provides a unified interface for key extraction that handles arrays (returning string indices), objects (returning property names), and other types with fallback iteration. Optimized for performance with direct array handling.

Signature​

const getKeys: <Value>(value: Value) => string[]

Parameters​

NameTypeDescription
value-Value to extract keys from (array, object, or other)

Returns​

Array of string keys representing indices or property names

Examples​

Array key extraction​

import { getKeys } from '@winglet/common-utils';

const array = ['a', 'b', 'c'];
console.log(getKeys(array)); // ['0', '1', '2']

const sparseArray = [1, , 3]; // sparse array
console.log(getKeys(sparseArray)); // ['0', '1', '2']

Object key extraction​

const obj = { name: 'John', age: 30, city: 'NYC' };
console.log(getKeys(obj)); // ['name', 'age', 'city']

const emptyObj = {};
console.log(getKeys(emptyObj)); // []

Mixed type handling​

console.log(getKeys('hello')); // ['0', '1', '2', '3', '4']
console.log(getKeys(123)); // []
console.log(getKeys(null)); // []
console.log(getKeys(undefined)); // []

Playground​

import { getKeys } from '@winglet/common-utils';

const array = ['a', 'b', 'c'];
console.log(getKeys(array)); // ['0', '1', '2']

const sparseArray = [1, , 3]; // sparse array
console.log(getKeys(sparseArray)); // ['0', '1', '2']

Notes​

Behavior by Type:

  • Arrays: Returns string indices ('0', '1', '2', etc.)
  • Objects: Returns own enumerable property names
  • Strings: Returns character indices
  • Other: Uses for...in loop with hasOwnProperty check

Performance: Optimized array handling with pre-allocated string array.