const typeOf = x => 

  ({}).toString

      .call(x)

      .match(/\[object (\w+)\]/)[1]

​

function areSimilar(a, b) {

  const everyKey = f => Object.keys(a).every(f)

​

  switch(typeOf(a)) {

    case 'Array':

      return a.length === b.length &&

        everyKey(k => areSimilar(a.sort()[k], b.sort()[k]));

    case 'Object':

      return Object.keys(a).length === Object.keys(b).length &&

        everyKey(k => areSimilar(a[k], b[k]));

    default:

      return a === b;

  }

}

​

//tests

​

console.clear();

console.assert(areSimilar({foo:'bar'}, {foo:'bar'}));

console.assert(!areSimilar({foo:'bar'}, {foo:'baz'}));

console.assert(areSimilar({}, {}));

console.assert(areSimilar({a:{}}, {a:{}}));

console.assert(!areSimilar({a:{b:[]}}, {a:{b:{}}}));

console.assert(areSimilar({a:{b:[2]}}, {a:{b:[2]}}));

console.assert(areSimilar({a:{b:[1, '{}']}}, {a:{b:[1, '{}']}}));

console.assert(areSimilar({a:{b:[1, '{}']}}, {a:{b:['{}', 1]}}));

console.assert(areSimilar({a:{b:[1, '{}', [3, '4', ['98']]]}}, {a:{b:[[['98'], 3, '4'], '{}', 1]}}));

​

console.assert(!areSimilar({a:{b:[1, null]}}, {a:{b:['{}', 1]}}));

console.assert(areSimilar({a:{b:[1, { bar: [1, 3, 2] }, '{}', null]}}, {a:{b:['{}', 1, {bar: [1, 2, 3]}, null]}}));