attributes required not work when clone element html : i have some elements with attribute required and i write jQuery code to clone this element when i press submit it should be show message must fill input but dosen't work just for this clone elements ...  so what's problem

     <div class='col-md-12'>
                    <div class='box box-primary'>
                        <div class='box-header with-border'>
                            <h3 class='box-title'>Information of Person</h3>
                        </div>
                      
                        <div class='form-group'>
                           <div class='box-body rowClone2'>
                                 
                                <div class='row rowClone'>
                                    
                                   <div class='col-xs-6 col-md-3'>
                                       <input type="text" class="form-control" required>
                                   </div>
                                   <div class='col-xs-6 col-md-3'>
                                        
                                        <input type="text" class="form-control" required>
                                    </div>
                                   
                                        <div class='col-xs-6 col-md-3' >
                                                
                                                <input type="tel" class="form-control">
                                            </div>
                                        
                                            <div class='col-xs-6 col-md-3'>
                                                   
                                                    <input type="text" class="form-control" required>
                                                </div>
                                               
                                              
                               </div>
                               
                                <br>
                                                
                            
                           </div>
                           <div class="row">
                               <div class="col-md-3">
                                   
                                    <input type="submit" value="Submit" formnovalidate>                                   
                               </div>
                           </div>
                       </div>
    