files/en-us/web/javascript/reference/global_objects/object/defineproperties/index.md

metadata

title: Object.defineProperties()
short-title: defineProperties()
slug: Web/JavaScript/Reference/Global_Objects/Object/defineProperties
page-type: javascript-static-method
browser-compat: javascript.builtins.Object.defineProperties
sidebar: jsref

The Object.defineProperties() static method defines new or modifies existing properties directly on an object, returning the object.

{{InteractiveExample("JavaScript Demo: Object.defineProperties()")}}

const object = {};

Object.defineProperties(object, {
  property1: {
    value: 42,
    writable: true,
  },
  property2: {},
});

console.log(object.property1);
// Expected output: 42

Syntax

Object.defineProperties(obj, props)

Parameters

• obj
  • : The object on which to define or modify properties.
• props

  • : An object whose keys represent the names of properties to be defined or modified and whose values are objects describing those properties. Each value in props must be either a data descriptor or an accessor descriptor; it cannot be both (see {{jsxref("Object.defineProperty()")}} for more details).

    Data descriptors and accessor descriptors may optionally contain the following keys:

    • configurable
      • : true if and only if the type of this property descriptor may be changed and if the property may be deleted from the corresponding object. Defaults to false.
    • enumerable
      • : true if and only if this property shows up during enumeration of the properties on the corresponding object. Defaults to false.

    A data descriptor also has the following optional keys:

    • value
      • : The value associated with the property. Can be any valid JavaScript value (number, object, function, etc.). Defaults to {{jsxref("undefined")}}.
    • writable
      • : true if and only if the value associated with the property may be changed with an {{jsxref("Operators", "assignment operator", "assignment_operators", 1)}}. Defaults to false.

    An accessor descriptor also has the following optional keys:

    • get
      • : A function which serves as a getter for the property, or {{jsxref("undefined")}} if there is no getter. The function's return value will be used as the value of the property. Defaults to {{jsxref("undefined")}}.
    • set
      • : A function which serves as a setter for the property, or {{jsxref("undefined")}} if there is no setter. The function will receive as its only argument the new value being assigned to the property. Defaults to {{jsxref("undefined")}}.

    If a descriptor has neither of value, writable, get and set keys, it is treated as a data descriptor. If a descriptor has both value or writable and get or set keys, an exception is thrown.

Return value

The object that was passed to the function.

Examples

Using Object.defineProperties

const obj = {};
Object.defineProperties(obj, {
  property1: {
    value: true,
    writable: true,
  },
  property2: {
    value: "Hello",
    writable: false,
  },
  // etc. etc.
});

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

• Polyfill of Object.defineProperties in core-js
• es-shims polyfill of Object.defineProperties
• {{jsxref("Object.defineProperty()")}}
• {{jsxref("Object.keys()")}}
• Enumerability and ownership of properties