title: Check visibility of item at the screen
body: <p>I have FlastList with data. I need to check if item from the Flastlist is seen. So if i do not see data at my screen i do not have to do anything, but if i see i have to console.log data info. And when i am scrolling i have to console.log data that is visibile. I am trying to use onViewableItemsChanged with viewabilityConfig, but when i console.log data, it returns all data from FlastList but not data that is seen. Help me please.</p>
  <p>I will be very thankfull!</p>
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>_onViewableItemsChanged = ({ viewableItems, changed }) =&gt; {
    
      console.log("Visible items are", viewableItems.map(item =&gt; item.item.text));
  };
    
  _viewabilityConfig = {
      viewAreaCoveragePercentThreshold: 100
  };
  
  //....
  
  &lt;FlatList
     data={this.state.postData}
     initialNumToRender={0}
     ItemSeparatorComponent = {this.FlatListItemSeparator}
     renderItem={({item}) =&gt; {
         return (
             &lt;View style={{paddingTop: 15}}
              ref={ (divElement) =&gt; { this.divElement = divElement } }
             &gt;
             // data
     
         )}
       }
     onViewableItemsChanged={this._onViewableItemsChanged}
     viewabilityConfig={this._viewabilityConfig}
     keyExtractor={item =&gt; item.id}
  /&gt;</code></pre>
  </div>
  </div>
  </p>