if else statements in react functional components code example

Example 1: ternary react

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

Example 2: 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 3: react if statement

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

Example 4: 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>
		)
	}
}