如何使用pouchdb在值中返回和存储文档？

var db = new PouchDB('mydb');

var doc = {
  _id: 'mydoc',
  title: 'My Document',
  content: 'This is my document.'
};

db.put(doc).then(function(response) {
  console.log('Document stored successfully.');
}).catch(function(error) {
  console.log('Error storing document: ' + error);
});

db.get('mydoc').then(function(doc) {
  console.log('Document retrieved successfully.');
  console.log(doc);
}).catch(function(error) {
  console.log('Error retrieving document: ' + error);
});

db.get('mydoc').then(function(doc) {
  doc.title = 'Updated Document';
  return db.put(doc);
}).then(function(response) {
  console.log('Document updated successfully.');
}).catch(function(error) {
  console.log('Error updating document: ' + error);
});

db.get('mydoc').then(function(doc) {
  return db.remove(doc._id, doc._rev);
}).then(function(response) {
  console.log('Document deleted successfully.');
}).catch(function(error) {
  console.log('Error deleting document: ' + error);
});