title: How to stop reactjs component rerender on state change
body: <p>I have a form with some input fields (some of them hidden until a checkbox is checked. When I check/uncheck the checkbox a specific state is set (<code>this.state.isChecked = true/false</code>). </p>
  
  <p>On render method, i have a div (containing some input fields) with some classes and this condition for "show" class: <code>&lt;div className={'extra-fields ' + (this.state.isChecked? ' show' : '')}&gt;...&lt;/div&gt;</code></p>
  
  <p>Expected behavior is that on state change, only the "show" class is putted or deleted from div
  Current behavior: the entire form is rendered again and all data written in the input fields are lost.</p>
  
  <p>How it should be done this?</p>