使用React.js和Elasticsearch实现。首先使用React.js创建搜索框组件，然后集成Elasticsearch查询功能实现即时搜索功能。代码示例如下：

import React, { useState, useEffect } from 'react';
import { Client } from '@elastic/elasticsearch';

const client = new Client({
  node: 'http://localhost:9200',
});

function SearchBar() {
  const [query, setQuery] = useState('');
  const [results, setResults] = useState([]);

  useEffect(() => {
    async function getResults() {
      const { body } = await client.search({
        index: 'contacts',
        body: {
          query: {
            match: {
              name: query,
            },
          },
        },
      });

      setResults(body.hits.hits);
    }

    getResults();
  }, [query]);

  function handleChange(event) {
    setQuery(event.target.value);
  }

  return (
    

      
      

        {results.map(result => (
          
{result._source.name}
        ))}
      
    
  );
}

export default SearchBar;