title: How update array in the state and show updated array with map() in reactjs
body: <p>i create a state and make an array in it i succeeded to push in array and map them ,
  but i cant show updated array in my view , how can i update state before show anything<br>
  my code is:</p>
  
  <pre><code>
  class App extends Component{
      constructor(){
          super()
         this.state = [
             {id:'1'  , title : ''},
             {id:'2'  , title : ''},
             {id:'3'  , title : ''}
         ]
  
  
      }
  
      increment = (a) =&gt;{
          this.state.push({id : ReactDOM.findDOMNode(this.refs.id).value , title : ReactDOM.findDOMNode(this.refs.user).value})
      }
  
  
  
  
      render(){
          return(
              &lt;div&gt;
                   &lt;input type="text" ref='id' placeholder='id'/&gt;
                  &lt;input type="text" ref='user' placeholder='user'/&gt;
                  &lt;button onClick={this.increment}&gt;+&lt;/button&gt;
                  &lt;ul&gt;{ 
                      this.state.map((item , id) =&gt; 
                      &lt;li key={id}&gt;
                      &lt;h1&gt;{item.title}&lt;/h1&gt;
                      &lt;/li&gt;)
                          }
                  &lt;/ul&gt;
              &lt;/div&gt;
          )
      }
          }
  </code></pre>