title: this.props.params not existing after passing parameter on react-router
body: <p>I'm passing parameter from react-router's route path to component but in this.props object, 'params' not existing</p>
  
  <pre><code>const routes = (
      &lt;Router forceRefresh={true}&gt;
          &lt;div&gt;
              &lt;Route exact path="/" component={Firstpage}/&gt;
              &lt;Route exact path="/projects" component={Projectslist}/&gt;
              &lt;Route exact path="/projects/:projectId" component={Singleproject}/&gt;
          &lt;/div&gt;
      &lt;/Router&gt;
  );
  </code></pre>
  
  <p>And this is my component:</p>
  
  <pre><code>class Singleproject extends React.Component{
      constructor(props) {
          super(props);
      }
  
      componentWillMount(){
          window.document.title = "Wploper | Project title";
      }
      render(){
          return(
              &lt;div&gt;
                  &lt;Mainheader/&gt;
                  &lt;div id="single-project-container" className="sheet-max-width"&gt;
                      &lt;h2&gt;{this.props.params}&lt;/h2&gt;
                  &lt;/div&gt;
                  &lt;Mainfooter/&gt;
              &lt;/div&gt;
          );
      }
  }
  </code></pre>
  
  <p>And the object (this.props) hasn't params:
  <a href="https://i.stack.imgur.com/TL5xV.png" rel="nofollow noreferrer">enter image description here</a></p>