Edit in JSFiddle

let obj = {
  name: {
    fName: 'Sachin',
    lName: 'Bachhav'
  },
  age: 30
};
let clone = {...obj};

clone.name.lName = 'Tendulkar';

console.log(JSON.stringify(obj,null,2));
console.log(JSON.stringify(clone,null,2));