Mongoose查找，使用一个搜索参数的多个字段

const mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/mydatabase', { useNewUrlParser: true });

const userSchema = new mongoose.Schema({
  name: String,
  age: Number,
  email: String
});

const User = mongoose.model('User', userSchema);

const searchParam = 'John'; // 搜索参数

User.find({
  $or: [
    { name: searchParam },
    { age: searchParam },
    { email: searchParam }
  ]
}, (err, users) => {
  if (err) {
    console.error(err);
  } else {
    console.log(users);
  }
});