ConditionalRenderFunction.js

// if declaración dentro de la función de representación, pero antes de la returndeclaración. 

import React from 'react';
import ReactDOM from 'react-dom';

class TodaysPlan extends React.Component {
  render() {
    let task;
    if (!apocalypse) {
      task = 'learn React.js'
    } else {
      task = 'run around'
    }

    return <h1>Today I am going to {task}!</h1>;
  }
}

ReactDOM.render(
	<TodaysPlan />,
	document.getElementById('app')
);

// Example 


import React from 'react';
import ReactDOM from 'react-dom';

const fiftyFifty = Math.random() < 0.5;

// New component class starts here:
class TonightsPlan extends React.Component {
  render() {
    if (fiftyFifty) {
      return <h1>Tonight I'm going out WOOO</h1>;
    } else {
      return <h1>Tonight I'm going to bed WOOO</h1>;
    }
  }
}

ReactDOM.render(
	<TonightsPlan />,
	document.getElementById('app')
);