The JavaScript bookmarklet for extracting WhatsApp Contacts traverses through the DOM of the WhatsApp Web client and gets the profile picture, the name and the phone number (with the country code) of all your WhatsApp contacts.

The list can be saved as a CSV file for importing into Google Contacts, you can send it to the printer or you can use download the entire web page to save the higher resolution profile pictures of your WhatsApp contacts on the desktop. You can manually upload these later to your Google Contacts.

function getWhatsAppAddressBook() {
  /* Switch to the All Contacts view in WhatsApp */
  $('button.icon-chat').click();

  var list = {},
    position = -1;

  if (position != $('div.drawer-body').scrollTop()) {
    $('div.chat').each(function (i) {
      /* Get the profile picture of the WhatsApp contact */
      var img = $(this).find('img.avatar-image.is-loaded');

      /* Extract the Contact Full Name */
      var title = $(this).find('div.chat-title');

      /* Extract the WhatsApp Phone number */
      var tel = img[0].src.match(/u=(\d*)/);

      /* Save the entry in an associated array */
      list[tel[1]] = { thumb: img[0].src, name: title[0].innerText };
    });

    position = $('div.drawer-body').scrollTop();
    $('div.drawer-body').scrollTop(position + 72);
  }

  console.log(list);
}