JavaScript (ES2026) reference · Object Methods

JavaScript Object.defineProperty() Method

Add or change one property with full control over whether it is writable, enumerable and configurable, or define a getter.

JavaScript (ES2026) Since ES5

Create a free account to save this page, take notes and track your progress. Sign in

Syntax

Object.defineProperty(obj, prop, descriptor)

Parameters

Parameter	Description
`obj`	The object to inspect or change.
`prop`	The property name.
`descriptor`	`{ value, writable, enumerable, configurable }` or `{ get, set }`.

Return value

The object.

Examples

A read-only propertyTry it yourself

"use strict";
const config = {};
Object.defineProperty(config, "version", { value: "1.0", writable: false, enumerable: true });
try { config.version = "2.0"; } catch (e) { console.log(e.constructor.name); }
console.log(config.version);

Output

TypeError
1.0

A computed, non-enumerable getterTry it yourself

const temp = { celsius: 20 };
Object.defineProperty(temp, "fahrenheit", { get() { return this.celsius * 9 / 5 + 32; } });
console.log(temp.fahrenheit, Object.keys(temp));