Reflect.defineProperty()

The static Reflect.defineProperty() method is like Object.defineProperty() but returns a Boolean.

Syntax

Reflect.defineProperty(target, propertyKey, attributes)

Parameters

target
The target object on which to define the property.
propertyKey
The name of the property to be defined or modified.
attributes
The attributes for the property being defined or modified.

Return value

A Boolean indicating whether or not the property was successfully defined.

Exceptions

A TypeError, if target is not an Object.

Description

The Reflect.defineProperty method allows precise addition to or modification of a property on an object. For more details see the Object.defineProperty which is similar. Object.defineProperty returns the object or throws a TypeError if the property has not been successfully defined. Reflect.defineProperty, however, simply returns a Boolean indicating whether or not the property was successfully defined.

Examples

Using Reflect.defineProperty()

var obj = {};
Reflect.defineProperty(obj, "x", {value: 7}); // true
obj.x; // 7

Checking if property definition has been successful

With Object.defineProperty, which returns an object if successful, or throws a TypeError otherwise, you would use a try...catch block to catch any error that occurred while defining a property. Because Reflect.defineProperty returns a Boolean success status, you can just use an if...else block here:

if (Reflect.defineProperty(target, property, attributes)) {
  // success
} else {
  // failure
}

Specifications

Specification Status Comment
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'Reflect.defineProperty' in that specification.
Standard Initial definition.
ECMAScript 2017 Draft (ECMA-262)
The definition of 'Reflect.defineProperty' in that specification.
Draft  

Browser compatibility

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari
Basic support 49 12 42 (42) No support No support 10
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support No support 49 42.0 (42) No support No support 10

See also

Document Tags and Contributors

 Contributors to this page: bsara, David_Gilbertson, eduardoboucas, gingerik, fscholz
 Last updated by: bsara,