Implementing HTTP methods (GET & POST) with json-server and React

Get.js

import React, { Component } from 'react';
import './App.css';

export default class Get extends Component {

    constructor(props) {
        super(props);
        this.state = {
            error: null,
            isLoaded: false,
            items: []
        }
    }

    componentDidMount() {
        let url = 'http://localhost:3001/items';
        fetch(url)
        .then(res => res.json())
        .then(data => {
            let items = data.map((item, index) => {
                return (
                    <div key={index}>
                        <h2>{item.id}</h2>
                        <h2>{item.name}</h2>
                        <h2>{item.price}</h2>
                    </div>
                )
            })
            this.setState({items: items});
        })
    }
    
  render() {
    return (
      <div className="MyApp">
        <header className="MyApp-header">
            <h1>hello world!</h1>
        </header>
        {this.state.items}
      </div>
    );
  }
}

Post.js

import React, { Component } from 'react';
import './App.css';

export default class Post extends Component {

    constructor(props) {
        super(props);
        this.state = {
            error: null,
            isLoaded: false,
            item: '',
            items: []
        };
        this.handleChange = this.handleChange.bind(this);
        this.handleSubmit = this.handleSubmit.bind(this);
    }

    handleChange(event) {
        this.setState({item: event.target.value});
    }

    handleSubmit(event) {
        event.preventDefault();
/*         this.setState({
            item: '',
            items: [...this.state.items, this.state.item]
        }); */
        let url = 'http://localhost:3001/items';
        fetch(url, {
            method: 'POST',
            body: {
                id: this.state.id,
                item: this.state.item
            }
        })
        .then(res => res.json())
        .then(data => {
            this.setState({
                isLoaded: true,
                items: [...this.state.items, this.state.item]
            })
            });
    }

/*     handleData() {
        
    }

    componentDidMount() {

    } */
    
  render() {
    return (
      <div className="MyApp">
        <header className="MyApp-header">
            <h1>hello world!</h1>
        </header>
        <form onSubmit={this.handleSubmit}>
            <input type="text" value={this.state.item} onChange={this.handleChange} />
        </form>
        {this.state.items.map((item, i) =>
        <p key={i}>{item}</p>
            )}
      </div>
    );
  }
}