title: How to sort array of objects based on number of nested sub-childs of objects?
body: <p>What is the best way to sort the following array in order on number of sub childs (i.e. number of <code>ISBN</code>s in this case).</p>
  
  <pre><code>const data = [{
        "Arnold Bennett": {
           "9781784872359": {
              "thumbnail_image_url": "https://books-sn.s3.amazonaws.com/571b8c01-ed88-4cc1-8e0c-efe3de967147.jpg",
              "title": "Clayhanger "
           }
        }
     },
     {
        "Agatha Christie": {
           "9780007527588": {
              "thumbnail_image_url": "http://books.google.com/books/content?id=BxlamwEACAAJ&amp;printsec=frontcover&amp;img=1&amp;zoom=1&amp;source=gbs_api",
              "title": "Mrs. McGinty's Dead"
           },
           "9780008129590": {
              "thumbnail_image_url": "https://books-sn.s3.amazonaws.com/c125ee1d-c5ea-4827-a488-e9ee9c8afc8d.jpg",
              "title": "The Clocks"
           },
           "9780007120857": {
              "thumbnail_image_url": "http://books.google.com/books/content?id=RAlvswEACAAJ&amp;printsec=frontcover&amp;img=1&amp;zoom=1&amp;source=gbs_api",
              "title": "The Murder at the Vicarage"
           },
           "9780007556878": {
              "thumbnail_image_url": "http://books.google.com/books/content?id=Zb_inQEACAAJ&amp;printsec=frontcover&amp;img=1&amp;zoom=1&amp;source=gbs_api",
              "title": "Dead Man's Folly"
           },
           "9780007120826": {
              "thumbnail_image_url": "http://books.google.com/books/content?id=Dve45zlLKbUC&amp;printsec=frontcover&amp;img=1&amp;zoom=1&amp;edge=curl&amp;source=gbs_api",
              "title": "4.50 from Paddington"
           },
           "9780007121052": {
              "thumbnail_image_url": "http://books.google.com/books/content?id=QR9J95ZE2zcC&amp;printsec=frontcover&amp;img=1&amp;zoom=1&amp;edge=curl&amp;source=gbs_api",
              "title": "Nemesis"
           },
           "9780007527519": {
              "thumbnail_image_url": "http://books.google.com/books/content?id=dOrsAQAACAAJ&amp;printsec=frontcover&amp;img=1&amp;zoom=1&amp;source=gbs_api",
              "title": "Five Little Pigs"
           },
           "9780007120963": {
              "thumbnail_image_url": "https://books-sn.s3.amazonaws.com/ba1fcb40-5383-40d9-bdfc-0e9d285b2321.jpeg",
              "title": "A Murder is Announced "
           },
           "9780008196233": {
              "thumbnail_image_url": "https://books-sn.s3.amazonaws.com/3a08b20a-377e-4b96-890c-1ecc3e09e595.jpg",
              "title": "The Sittaford Mystery"
           },
           "9780008196615": {
              "thumbnail_image_url": "http://books.google.com/books/content?id=6E8FvgAACAAJ&amp;printsec=frontcover&amp;img=1&amp;zoom=1&amp;source=gbs_api",
              "title": "At Bertram's Hotel"
           },
           "9780008129484": {
              "thumbnail_image_url": "https://books-sn.s3.amazonaws.com/fe46e96d-7f24-40f1-92e1-b60f10af9dd1.jpg",
              "title": "The Mystery of the Blue Train"
           },
           "9780007314669": {
              "thumbnail_image_url": "https://books-sn.s3.amazonaws.com/cd40bc91-4c28-4f97-872a-ba24f10b0564.jpg",
              "title": "An Autobiography"
           },
           "9780006513773": {
              "thumbnail_image_url": "http://books.google.com/books/content?id=JMqChKyf-0EC&amp;printsec=frontcover&amp;img=1&amp;zoom=1&amp;edge=curl&amp;source=gbs_api",
              "title": "Hercule Poirot"
           },
           "9780007527502": {
              "thumbnail_image_url": "http://books.google.com/books/content?id=9CO1mgEACAAJ&amp;printsec=frontcover&amp;img=1&amp;zoom=1&amp;source=gbs_api",
              "title": "Murder on the Orient Express"
           },
           "9780007527496": {
              "thumbnail_image_url": "http://books.google.com/books/content?id=ERPosgEACAAJ&amp;printsec=frontcover&amp;img=1&amp;zoom=1&amp;source=gbs_api",
              "title": "The Mysterious Affair at Styles"
           },
           "9780007120833": {
              "thumbnail_image_url": "http://books.google.com/books/content?id=lA1KuAEACAAJ&amp;printsec=frontcover&amp;img=1&amp;zoom=1&amp;source=gbs_api",
              "title": "The Body in the Library"
           },
           "9780007120734": {
              "thumbnail_image_url": "http://books.google.com/books/content?id=CEEUPYluIeEC&amp;printsec=frontcover&amp;img=1&amp;zoom=1&amp;edge=curl&amp;source=gbs_api",
              "title": "Five Little Pigs"
           },
           "9780007120970": {
              "thumbnail_image_url": "https://books-sn.s3.amazonaws.com/fd1f1d09-c08f-4f35-8be1-a35862d9e4b6.jpg",
              "title": "A Pocket Full of Rye"
           },
           "9780007120864": {
              "thumbnail_image_url": "http://books.google.com/books/content?id=MK9JNwoZAncC&amp;printsec=frontcover&amp;img=1&amp;zoom=1&amp;edge=curl&amp;source=gbs_api",
              "title": "The Thirteen Problems"
           },
           "9780008125929": {
              "thumbnail_image_url": "http://books.google.com/books/content?id=kxK7rQEACAAJ&amp;printsec=frontcover&amp;img=1&amp;zoom=1&amp;source=gbs_api",
              "title": "The Secret Adversary (隱身魔鬼)"
           },
           "9780007121069": {
              "thumbnail_image_url": "http://books.google.com/books/content?id=ddlQBfuKWzwC&amp;printsec=frontcover&amp;img=1&amp;zoom=1&amp;edge=curl&amp;source=gbs_api",
              "title": "Sleeping Murder"
           },
           "9780008164898": {
              "thumbnail_image_url": "http://books.google.com/books/content?id=JCX2sgEACAAJ&amp;printsec=frontcover&amp;img=1&amp;zoom=1&amp;source=gbs_api",
              "title": "Cards on the Table"
           }
        }
     }, {
        "Alain De Botton": {
           "9780141035192": {
              "thumbnail_image_url": "http://books.google.com/books/content?id=l4FGPwAACAAJ&amp;printsec=frontcover&amp;img=1&amp;zoom=1&amp;source=gbs_api",
              "title": "The Consolations of Philosophy"
           }
        }
     }, {
        "Alan Hollinghurst": {
           "9781447275183": {
              "thumbnail_image_url": "https://books-sn.s3.amazonaws.com/b46fc3f6-4950-4e4d-a734-93abd10b5351.jpeg",
              "title": "The Line of Beauty"
           }
        }
     }, {
        "Alan MacDonald": {
           "9781407108315": {
              "thumbnail_image_url": "http://books.google.com/books/content?id=1aEGOwAACAAJ&amp;printsec=frontcover&amp;img=1&amp;zoom=1&amp;source=gbs_api",
              "title": "Winston Churchill and His Woeful Wars"
           }
        }
     }, {
        "Aldous Huxley": {
           "9780099518471": {
              "thumbnail_image_url": "http://books.google.com/books/content?id=3zl4oJMUskoC&amp;printsec=frontcover&amp;img=1&amp;zoom=1&amp;edge=curl&amp;source=gbs_api",
              "title": "Brave New World"
           }
        }
     }, {
        "Alessandro Manzoni": {
           "9780140442748": {
              "thumbnail_image_url": "http://books.google.com/books/content?id=azLiQUtMSncC&amp;printsec=frontcover&amp;img=1&amp;zoom=1&amp;edge=curl&amp;source=gbs_api",
              "title": "The Betrothed"
           },
           "9780241259078": {
              "thumbnail_image_url": "http://books.google.com/books/content?id=nyo8jwEACAAJ&amp;printsec=frontcover&amp;img=1&amp;zoom=1&amp;source=gbs_api",
              "title": "The Betrothed"
           }
        }
     }
  ]
  </code></pre>
  
  <p>I want to sort so that I get <code>Agatha Christie</code> on top and then <code>Alessandro Manzoni</code> and then the rest of them in order of child elements they have.</p>
  
  <p>Thanks</p>