关于一段react代码片段 有点疑问

Question

import React, { Component, PropTypes } from 'react';
import { browserHistory } from 'react-router';

class SearchGithub extends Component {
    static PropTypes = {
        history: PropTypes.object.isRequired
    }
    getRef(ref){
        this.usernameRef = ref;
        console.log(ref);
    }
    handleSubmit(event){
        const username = this.usernameRef.value;
        this.usernameRef.value = '';

        const path = `/profile/${username}`;
        browserHistory.push(path)

    }
    render(){
        return (
            <div className="col-sm-12">
                <form onSubmit={() => this.handleSubmit()}>
                    <div className="form-group col-sm-7">
                        <input type="text" className="form-control" ref={(ref) => this.getRef(ref)} />
                    </div>
                    <div className="form-group col-sm-5">
                        <button type="submit" className="btn btn-block btn-primary">搜索 Github</button>
                    </div>
                </form>
            </div>
        )
    }
}

export default SearchGithub;

这是一个搜索组件，上面的：

getRef(ref){
        this.usernameRef = ref;
        console.log(ref);
    }

函数与下面的

<input type="text" className="form-control" ref={(ref) => this.getRef(ref)} />
这是什么意思啊 大家有知道的或者这么用的吗

Answer 1

https://facebook.github.io/re...