​

myObject = { 'a': 1, 'b': 2, 'c': 3, d: { 'a': 1, 'b': 2, 'c': 3 }}

​

​

    const sqrObjRecursive = (obj) => 

      Object.keys(obj).reduce((p, c) => 

        (obj[c] && typeof obj[c] === 'object') ?

          {...p, ...{[c]: sqrObjRecursive(obj[c])}} :

          {...p, ...{[c]: obj[c] * obj[c]}}, {})

​

console.log(sqrObjRecursive(myObject));

​