JAVASCRIPT

state in react

class BalanceInquiry extends Component {
  constructor(props) {
    super(props);
    this.state = {
      totalIncome: 0,
    };
  }

  render() {
    return <div>totalIncome {this.state.totalIncome}</div>;
  }
}

what is state in react

// State is essentially a global class variable
// that is modified when the component updates

class Clock extends React.Component {
  constructor(props) {
    super(props);
    this.state = {date: new Date()};
  }

  render() {
    return (
      <div>
        <h1>Hello, world!</h1>
        <h2>It is {this.state.date.toLocaleTimeString()}.</h2>
      </div>
    );
  }
}

react state

import React, { Component } from "react";

class Counter extends Component {
	// you can either initialize state inside constructor
  	constructor() {
		super();
		this.state = {
			count: 1,
			tags: ["tag1", "tag2", "tag3"],
		};
	}
  	// or initialize the state as class field declaration
  	state = {
		count: 1,
		tags: ["tag1", "tag2", "tag3"],
	};
}

react state

import React from 'react';

const App = () => {
  const accordionData = {
    title: 'Section 1',
    content: `Lorem ipsum dolor, sit amet consectetur adipisicing elit. Quis sapiente
      laborum cupiditate possimus labore, hic temporibus velit dicta earum
      suscipit commodi eum enim atque at? Et perspiciatis dolore iure
      voluptatem.`
  };

  const { title, content } = accordionData;

  return (
    <React.Fragment>
      <h1>React Accordion Demo</h1>
      <div className="accordion">
        <div className="accordion-item">
          <div className="accordion-title">
            <div>{title}</div>
            <div>+</div>
          </div>
          <div className="accordion-content">{content}</div>
        </div>
      </div>
    </React.Fragment>
  );
};

export default App;

React state

  const [customers, setCustomers] = useState([]);
  const [nextPageURL, setNextPageURL] = useState('');

react state

<div className="accordion">
  <div className="accordion-item">
    <div
      className="accordion-title"
      onClick={() => setIsActive(!isActive)}
    >
      <div>{title}</div>
      <div>{isActive ? '-' : '+'}</div>
    </div>
    {isActive && <div className="accordion-content">{content}</div>}
  </div>
</div>