JavaScript Reflect setPrototypeOf() Method

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JavaScript Reflect.setPrototypeOf() method in JavaScript is used to set the prototype of a specified object to another object or to Null. This method returns the boolean value for the operation that is successful. This method is the same as the Object.setPrototypeOf() method.

Syntax:

Reflect.setPrototypeOf(obj, prototype)

Parameters:

Obj: This parameter holds the target object and it is used to set the prototype.
Prototype: This parameter holds the object’s new prototype. It can be any object or simply a null.

Return value: This method always returns a Boolean value which indicates whether setting the prototype was successfully done or not.

Exceptions: A TypeError is an exception given as the result when the target is not an object.

Below examples illustrate the Reflect.setPrototypeOf() method in JavaScript:

Example 1: In this example, we will set the prototype of an object using the Reflect.setPrototypeOf() method in JavaScript.

javascript

const object1 = {}; 
  
console.log(Reflect.setPrototypeOf(object1, Object.prototype)); 
console.log(Reflect.setPrototypeOf(object1, null)); 
  
const object2 = {}; 
console.log(Reflect.setPrototypeOf(Object.freeze(object2), null)); 
  
let object3 = { 
    gfg() { 
        return 'value'; 
    } 
} 
let obj = { 
    zambiatek() { 
        return 'answer'; 
    } 
} 
Object.setPrototypeOf(obj, object3); 
console.dir(obj); 
console.log(obj.zambiatek()); 
console.log(obj.gfg());

Output:

true
true
false
"answer"
"value"

Example 2: In this example, we will set the prototype of an object using the Reflect.setPrototypeOf() method in JavaScript.

javascript

console.log(Reflect.setPrototypeOf({}, Object.prototype)); 
  
// It can change an object's [[Prototype]] to null. 
console.log(Reflect.setPrototypeOf({}, null)); 
  
// Returns false if target is not extensible. 
console.log(Reflect.setPrototypeOf(Object.freeze({}), null)); 
  
// Returns false if it cause a prototype chain cycle. 
let target = {} 
let proto = Object.create(target) 
console.log(Reflect.setPrototypeOf(target, proto)); 
  
let object3 = { 
    gfg() { 
        console.log(this.name + ' have fun.'); 
    } 
}; 
class objt { 
    constructor(name) { 
        this.name = name; 
    } 
} 
Reflect.setPrototypeOf(objt.prototype, object3); 
  
// If you do not do this you will get 
// a TypeError when you invoke speak   
let val = new objt('Geeks'); 
val.gfg();

Output:

true
true
false
false
"Geeks have fun."

Supported Browsers: The browsers supported by JavaScript Reflect.setPrototypeOf() method are listed below:

Google Chrome 49 and above
Edge 12 and above
Firefox 42 and above
Opera 36 and above
Safari 10 and above

We have a complete list of Javascript Reflects methods, to check those go through the JavaScript Reflect Reference article.

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