array as state in react code example

Example 1: how to add array data on state react

this.setState({ myArray: [...this.state.myArray, 'new value'] }) //simple value
this.setState({ myArray: [...this.state.myArray, ...[1,2,3] ] }) //another array

Example 2: add items to a react array in hooks

const addMessage = (newMessage) => setMessages(state => [...state, newMessage])

Example 3: react list based on state

import React, { Component } from 'react'; class App extends Component {  constructor(props) {    super(props);     this.state = {      list: [        { id: '1', age: 42 },        { id: '2', age: 33 },        { id: '3', age: 68 },      ],    };  }   onRemoveItem = id => {    this.setState(state => {      const list = state.list.filter(item => item.id !== id);       return {        list,      };    });  };   render() {    return (      <div>        <ul>          {this.state.list.map(item => (            <li key={item.id}>              The person is {item.age} years old.              <button                type="button"                onClick={() => this.onRemoveItem(item.id)}              >                Remove              </button>            </li>          ))}        </ul>      </div>    );  }} export default App;

Example 4: add items to a react array in hooks

const addMessage = (newMessage) => setMessages(state => [newMessage, ...state])