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Reflect.setPrototypeOf()

The Reflect.setPrototypeOf() static method is like Object.setPrototypeOf() but returns a Boolean. It sets the prototype (i.e., the internal [[Prototype]] property) of a specified object.

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Syntax

js
Reflect.setPrototypeOf(target, prototype)

Parameters

target

The target object of which to set the prototype.

prototype

The object's new prototype (an object or null).

Return value

A Boolean indicating whether or not the prototype was successfully set.

Exceptions

TypeError

Thrown if target is not an object or if prototype is neither an object nor null.

Description

Reflect.setPrototypeOf() provides the reflective semantic of setting the prototype of an object. At the very low level, setting the prototype returns a boolean (as is the case with the proxy handler). Object.setPrototypeOf() provides nearly the same semantic, but it throws a TypeError if the status is false (the operation was unsuccessful), while Reflect.setPrototypeOf() directly returns the status.

Reflect.setPrototypeOf() invokes the [[SetPrototypeOf]] object internal method of target.

Examples

Using Reflect.setPrototypeOf()

js
Reflect.setPrototypeOf({}, Object.prototype); // true

// It can change an object's [[Prototype]] to null.
Reflect.setPrototypeOf({}, null); // true

// Returns false if target is not extensible.
Reflect.setPrototypeOf(Object.freeze({}), null); // false

// Returns false if it cause a prototype chain cycle.
const target = {};
const proto = Object.create(target);
Reflect.setPrototypeOf(target, proto); // false

Specifications

Browser compatibility

Desktop Mobile Server
Chrome Edge Firefox Opera Safari Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet WebView Android Deno Node.js
setPrototypeOf 49 12 42 36 10 49 42 36 10 5.0 49 1.0 6.0.0

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Reflect/setPrototypeOf