title: Will react re-render only children in which some part of the state has changed or are all children that use the state are re-rendered?
body: <p>Consider the following scenario in a component.</p>
  
  <pre><code>export default class Dummy extends React.Component{
         state = {
            A: some data
            B: other data
            C: extra data
         }
  
         somefunction = () =&gt; {
             this.setState({A: changed Data});
         }
  
         render(){
              return(
                   &lt;ChildA data={this.state.A} callBackFunction={this.somefunction}/&gt;
                   &lt;ChildB data={this.state.B}/&gt;
                   &lt;ChildC data={this.state.C}/&gt;
              );
         }
  }
  </code></pre>
  
  <p>That is, if State 'A' is changed, will ChildA only be re-rendered (because it is only associated with 'A') or all the children be re-rendered (because they are associated with state in general)?</p>