mdn object assign

var x = {myProp: "value"};
var xClone = Object.assign({}, x);

//Obs: nested objects are still copied as reference.

const target = { a: 1, b: 2 };
const source = { b: 4, c: 5 };

const returnedTarget = Object.assign(target, source);

console.log(target);
// expected output: Object { a: 1, b: 4, c: 5 }

console.log(returnedTarget);
// expected output: Object { a: 1, b: 4, c: 5 }

The Object.assign() method copies all enumerable own properties from one or more source objects to a target object. It returns the target object.
const target = { a: 1, b: 2 };
const source = { b: 4, c: 5 };

const returnedTarget = Object.assign(target, source);

console.log(target);
// expected output: Object { a: 1, b: 4, c: 5 }

console.log(returnedTarget);
// expected output: Object { a: 1, b: 4, c: 5 }

let voleur = {
     action     : () =>console.log ('Coup de dague fatal') ,
     crie      : ('pour la horde!!!!') ,
     coupfatal :()=> console.log ('coup dans le dos')

}

voleur.action() ;
voleur.coupfatal() ;
console.log(voleur.crie) ;