title: What is the difference between using this.props and props in React.js?
body: <p>I've been using <code>this.props</code> and <code>props</code> interchangeably, and for the most part, there doesn't seem to be a major difference between them (as far as I can tell). </p>
  
  <p>However, I've been running into issues lately that make me think that when and why one is used over the other matters. </p>
  
  <p>This is where I'm currently using them interchangeably:</p>
  
  <pre><code>  constructor(props, context) {
      super(props, context);
      this.data    = props.card.data;
      this.dataLength = this.props.card.data.length;
    }
  </code></pre>
  
  <p>What's the difference and when do you use one over the other, and where? 
  Thanks!</p>