how to do conditional rendering in react code example

Example 1: react native conditional rendering

class Component extends React.Component {
	const a = true
	render() {
      return (
    	<Container>
          {a == true
           ? (<Button/>)
           : null
          }
        </Container>    	
	  )
	}
}

This is staying: if a == true, render a button component. 
Otherwise render null, in other words nothing.

Example 2: ternary react

render() {
  const isLoggedIn = this.state.isLoggedIn;
  return (
    <div>
      The user is <b>{isLoggedIn ? 'currently' : 'not'}</b> logged in.    
	</div>
  );
}

Example 3: react native conditional rendering

function Mailbox(props) {
  const unreadMessages = props.unreadMessages;
  return (
    <div>
      <h1>Hello!</h1>
      {unreadMessages.length > 0 &&
        <h2>
          You have {unreadMessages.length} unread messages.
        </h2>
      }
    </div>
  );
}

Example 4: conditional rendering react

function Mailbox(props) {
  const unreadMessages = props.unreadMessages;
  return (
    <div>
      <h1>Hello!</h1>
      {unreadMessages.length > 0 &&        <h2>          You have {unreadMessages.length} unread messages.        </h2>      }    </div>
  );
}

const messages = ['React', 'Re: React', 'Re:Re: React'];
ReactDOM.render(
  <Mailbox unreadMessages={messages} />,
  document.getElementById('root')
);

Example 5: conditional rendering react

import React, { Component } from 'react';

// @params [] * denotes optional param (we will need to use conditional rendering for some of these)
// [type](Bulma CSS class): Hero type, focuses on the base styling
// size(Bulma CSS Class): The size of the hero, small, medium, large, etc...
// heading: The main heading
// [subheading]: The subheading if desired
// [alignment](Bulma CSS Class): Aligns the content horizontally

// This Simple HeroComponent is bases upon the following
// https://bulma.io/documentation/layout/hero/ 

export class HeroComponent extends Component
{
	render() {
		return (
          	// The following ternary simply applies a class if it has been specified
			<section className={"hero" + (this.props.type ? " " + this.props.type + " " : " ") + this.props.size}>
				<div className="hero-body">
                  	// Again, another ternary applying a class... blah blah blah....
					<div className={"container" + this.props.alignment ? " " + this.props.alignment : ""}>
						<h1 className="title">{this.props.heading}</h1>
						// So, to answer the question...
						// The following is one way to do conditional rendering, probably the simplest and cleanest
						// If this.props.subheading exists, render <h2 .. />
						{this.props.subheading && <h2 className="subtitle">{this.props.subheading}</h2>}
					</div>
				</div>
			</section>
		)
	}
}