title: What is the difference between shouldComponentUpdate and componentWillUpdate in React?
body: <p>I have a doubt , when we are using react component methods there are methods with same behavior, and also they are called one by one in the component life cycle ? then what is the major difference,</p>
  
  <pre><code>shouldComponentUpdate(nextProps, nextState){
    // It will be executed with nextProps and nextState
  } 
  componentWillUpdate(nextProps, nextState){
    // It will be executed first with same data nextProps, nextState
  } 
  </code></pre>
  
  <p>In the above example We have same parameter data with same behavior but the shouldComponentUpdate will be called first.</p>
  
  <p><strong>Then what is the main difference ?</strong></p>