decpk

const arr = [10,20, , ,50];
console.log( arr );
console.log( arr[0] );		// output: 10
console.log( arr[2] );		// output: undefined

decpk

// In some script or third party package. It is highly unlikely chance to get this type of script.
Array.prototype['2'] = 'Praveen kumar'; 

// Our script
const arr = [10,20, , ,50];
console.log( arr );
console.log( arr[0] );		// output: 10
console.log( arr[2] );		// output: Praveen kumar

decpk

import React from 'react';
import ReactDOM from 'react-dom';
import App from './components/App';

ReactDOM.render(
    <App />,
    document.querySelector( '#root' )
);

decpk

const React = require( 'react' );
const CreateReactClass = require( 'create-react-class' );

const App = CreateReactClass( {
    render() {
        return React.createElement( 'h1', null, 'Hello world' );
    }
} )

export default App;

decpk

const React = require( 'react' );

class App extends React.Component{

    render() {
        return (
            <h1>Hello world</h1>
        )
    }
}

decpk

const React = require( 'react' );
const CreateReactClass = require( 'create-react-class' );

const App = CreateReactClass( {
    getInitialState() {
        return {
            message: 'world'
        }
    },
    render() {

decpk

import React, { Component } from 'react';

class App2 extends Component {
    constructor( props ) {
        super( props );
        this.state = {
            message: 'world'
        }
    }
    render() {

decpk

import React, { Component } from 'react';

class App2 extends Component {

    state = {
        message: 'world'
    }
    render() {
        return (
            <h1>Hello {this.state.message} in ES6 classes outside of constuctor</h1>

decpk

const React = require( 'react' );
const CreateReactClass = require( 'create-react-class' );

const App = CreateReactClass( {
    getDefaultProps() {
        return {
            message: 'world'
        }
    },
    render() {

decpk

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

class App extends Component {
    render() {
        return (
            <h1>Hello {this.props.message}</h1>
        );
    }
}