object.hasown

What is object.hasown?

The object.hasown npm package is a polyfill for the `Object.hasOwn` method, which is a standardized way of checking if an object has a property as its own (not inherited from its prototype chain). This package provides a reliable way to perform this check across different JavaScript environments, including those that do not support the `Object.hasOwn` method natively.

What are object.hasown's main functionalities?

Checking for own property

This feature allows you to check if an object has a specific property as its own. The code sample demonstrates checking for the existence of properties 'a' and 'b' on an object.

const hasOwn = require('object.hasown');
const object = { a: 1 };
const hasA = hasOwn(object, 'a'); // true
const hasB = hasOwn(object, 'b'); // false

Other packages similar to object.hasown

has

The 'has' package is a similar function that checks for the existence of a property in an object. It is similar to object.hasown but does not specifically check for own properties, meaning it could return true for inherited properties as well.

lodash.has

Lodash's 'has' function is part of the larger lodash utility library. It checks if `path` is a direct property of `object`. While similar, lodash's implementation allows checking deep paths, not just top-level properties, which is not a feature of object.hasown.

README

object.hasown

An ES spec-compliant Object.hasOwn shim. Invoke its "shim" method to shim Object.hasOwn if it is unavailable or noncompliant.

This package implements the es-shim API interface. It works in an ES3-supported environment and complies with the spec.

Most common usage:

var assert = require('assert');
var hasOwn = require('object.hasown');

var obj = { a: 1, b: 2 };

assert(hasOwn(obj, 'a'));
assert(hasOwn(obj, 'b'));
assert('toString' in obj && !hasOwn(obj, 'toString'));

if (!Object.hasOwn) {
	hasOwn.shim();
}

assert.deepEqual(Object.hasOwn(obj, 'a'), hasOwn(obj, 'a'));

Tests

Simply clone the repo, npm install, and run npm test

Changelog

v1.1.4 - 2024-03-22

Commits

• [meta] remove useless ESM 28440a5
• [actions] remove redundant finisher 579b54d
• [Deps] update es-abstract f7f9aa1
• [Dev Deps] update call-bind, npmignore, tape 8a2f213
• [Refactor] use es-object-atoms instead of es-abstract f0efe3b
• [Dev Deps] update call-bind, tape 683b500
• [Deps] update define-properties, es-abstract f74ecf2
• [meta] add missing engines.node 7ca6eeb
• [Deps] update es-abstract d5aa232
• [Dev Deps] update aud 26fa7f9