title: Curly braces declaring a variable in React
body: <p>Studying React right now. I am on the stage of Router and found some code in their documentation that I do not understand. (they use a lot of short-syntax operators and other stuff so it is hard to google or come up with idea what it is for). </p>
  
  <p>So here is <a href="https://reacttraining.com/react-router/web/example/auth-workflow" rel="noreferrer">code</a>: </p>
  
  <pre><code>const { from } = this.props.location.state || { from: { pathname: "/" } };
  const { redirectToReferrer } = this.state;
  </code></pre>
  
  <p>While declaring "something" on the left it is inside of <code>{ }</code>, why? </p>