title: React / Redux: mapStateToProps() is called many times
body: <p>I'm writing simple app using React / Redux. I notice that function mapStateToProps() is called many times. Here`s code:</p>
  
  <pre><code>class Employees extends React.Component {
      componentDidMount() {
          this.props.fetchEmployees();
      }
  }
  
  let mapStateToProps = function mapStateToProps(state) {
      console.log("foo");
      return {...};
  };
  
  let mapDispatch = (dispatch) =&gt; {
      return {
          fetchEmployees: bindActionCreators(fetchEmployees, dispatch)
      };
  };
  
  export default connect(mapStateToProps, mapDispatch)(Employees);
  </code></pre>
  
  <p>And what I get in console: </p>
  
  <p><a href="https://i.stack.imgur.com/o0Sjy.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/o0Sjy.png" alt="enter image description here"></a></p>
  
  <p>Is it normal or I'm doing something wrong? </p>