javascript - page is getting refress after uploading a file -

i trying upload file using ajax function , file getting uploaded problem after few time page getting refresh data has gone. please me prevent page load.

my html code is:

<form>     <input type="file" name="upl" id="upl" /><br />          <input type="submit" name="submit" id="submit" /> </form> <p id="res"></p> 

my js file code is:

$("#upl").on('change',function(e){         e.preventdefault();         e.stoppropagation();         var file_data = $(this).prop('files')[0];          var form_data = new formdata();                           form_data.append('file', file_data);         $.ajax({         url: 'upload.php', // point server-side php script          datatype: 'text',  // expect php script, if         cache: false,         contenttype: false,         processdata: false,         data: form_data,                                  type: 'post',         success: function(php_script_response){             $("#res").append(php_script_response); // display response php script, if             if(php_script_response){             return false;             }         }     }); }); 

and php file code is:

<?php  if ( 0 < $_files['file']['error'] ) {     echo 'error: ' . $_files['file']['error'] . '<br>'; } else {    if( move_uploaded_file($_files['file']['tmp_name'], 'uploads/' . $_files['file']['name']) ){    echo "uploaded";    }    else{    echo "not uploaded";    } }  ?> 

please solve problem.

because havent added action form , want use ajax no need of form.