如何在每次保存时使用Mongoose模式更新当前日期的属性？

const mongoose = require('mongoose');

const Schema = mongoose.Schema;

const ExampleSchema = new Schema({
  name: String,
  updatedAt: {
    type: Date,
    default: Date.now
  }
});

ExampleSchema.pre('save', function(next) {
  this.updatedAt = Date.now();
  next();
});

const ExampleModel = mongoose.model('Example', ExampleSchema);

const example = new ExampleModel({ name: 'example' });

example.save(function(err) {
  if (err) {
    console.error(err);
  } else {
    console.log('Document saved successfully');
  }
});