JavaScript: Object.setPrototypeOf

New in JS2015.

Object.setPrototypeOf(obj, parent)

Set the parent of obj to parent. Return the changed obj.

let aa = {};
let bb = Object.create (aa);

// bb's parent is aa
console.log( Reflect.getPrototypeOf ( bb ) === aa ); // true

// now change parent
let cc = Object.setPrototypeOf ( bb, Array );

// return value is the new bb
console.log( cc === bb ); // true
console.log( Reflect.getPrototypeOf ( bb ) === Array ); // true

[see Prototype and Inheritance]