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 = { neveropen() { return 'answer'; } } Object.setPrototypeOf(obj, object3); console.dir(obj); console.log(obj.neveropen()); 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.
