如果要执行基于文本的搜索，可以将$or运算符与正则表达式或文本搜索结合使用。

const MongoClient = require('mongodb').MongoClient;

const url = 'mongodb://localhost:27017';
const dbName = 'your_database_name';
const client = new MongoClient(url);
client.connect(function(err) {
  console.log('Connected successfully to server');

  const db = client.db(dbName);
  const collection = db.collection('userRegister');

  // Create an index on the fields you want to search
  collection.createIndex({ name: 'text', age: 'text', mobileno: 'text', email: 'text' });

  // Define your search query
  const query = {
    $or: [
      { name: { $regex: 'search_term', $options: 'i' } }, // Case-insensitive regex search for name
      { age: { $regex: 'search_term', $options: 'i' } }, // Case-insensitive regex search for age
      { mobileno: { $regex: 'search_term', $options: 'i' } }, // Case-insensitive regex search for mobileno
      { email: { $regex: 'search_term', $options: 'i' } }, // Case-insensitive regex search for email
      // ...
    ]
  };

  collection.find(query).toArray(function(err, docs) {
    console.log('Found the following records:');
    console.log(docs);
  });
  
  client.close();
});

字符串