React+axios implements github search user function (sample code)

import React, { Component } from 'react'
import "./App.css"
import Header from './commons/Header'
import List from './commons/List'
export default class App extends Component {
  // Initialize state
  state={
    users:[],
    isloading:false,
    isfirst:true,
    err:''

  }
  update=(updatemessage)=>{
     this.setState(
      updatemessage
     )
  }
  render() {
    return (
      <div className="container">
        <Header update={this.update} />
        <List users={this.state}></List>
      </div>
    )
  }
}

import React, { Component } from 'react'
import axios from "axios"

export default class Header extends Component {
  search=()=>{
     console.log(this.searchbtn.value);
     this.props.update({isfirst:false, isloading:true})
     axios.get(`http://localhost:3000/api1/search/users?q=${this.searchbtn.value}`).then(
      // Callback response upon success=>{
        
         console.log("Send request successfully",response.data.items);
         this.props.update({users: response.data.items,isloading:false})
       },
      // Callback error upon failure=>{
        this.props.update({err:error.message,isloading:false})
          console.log("failed",error.message);
      }
     )
  } 

    render() {
        return (
            <section className="jumbotron">
            <h3 className="jumbotron-heading">Search Github Users</h3>
            <div>
              <input type="text" placeholder="enter the name you search" 
               ref={c=>this.searchbtn=c}
              />
              &nbsp;
              <button onClick={this.search}>Search</button>
            </div>
          </section>
        )
    }
}

import React, { Component } from 'react'
import Listitem from './Listem'

export default class List extends Component {
  render() {
    return (
      <div className="row">
        {
          this.props.users.isfirst ? <h2 style={{margin:"50px"}}>Welcome to use, please enter the keyword</h2> :
          this.props.users.isloading ? <h2 style={{margin:"50px"}}>Loading......</h2> :
          this.props.users.err ? <h2 style={{margin:"50px"}}>{this.props.users.err}</h2> :
          this.props.users.users.map((a) => {
                  return (
                    <Listitem key={a.id} users={a} />
                  )
                })
        }
      </div>
    )
  }
}

import React, { Component } from 'react'
import "./index.css"
export default class Listitem extends Component {
 
    render() {
        return (
            <div className="card" >
            <a href={this.props.users.html_url} target="_blank" >
              <img src={this.props.users.avatar_url} style={{ width: '100px' }} />
            </a>
            <p className="card-text">{this.props.users.login}</p>
          </div>
        )
    }
}