title: page is getting refress after uploading a file
body: <p>I am trying to upload a file using ajax function and the file is getting uploaded but the problem is after few time my page is getting refresh so my all the data has gone.
  Please help me to prevent the page from the load.</p>
  
  <p>My HTML code is:</p>
  
  <pre><code>&lt;form&gt;
      &lt;input type="file" name="upl" id="upl" /&gt;&lt;br /&gt;     
      &lt;input type="submit" name="submit" id="submit" /&gt;
  &lt;/form&gt;
  &lt;p id="res"&gt;&lt;/p&gt;
  </code></pre>
  
  <p>My js file code is:</p>
  
  <pre><code>$("#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 to server-side PHP script 
          dataType: 'text',  // what to expect back from the PHP script, if anything
          cache: false,
          contentType: false,
          processData: false,
          data: form_data,                         
          type: 'post',
          success: function(php_script_response){
              $("#res").append(php_script_response); // display response from the PHP script, if any
              if(php_script_response){
              return false;
              }
          }
      });
  });
  </code></pre>
  
  <p>and my php file code is: </p>
  
  <pre><code>&lt;?php
  
  if ( 0 &lt; $_FILES['file']['error'] ) {
      echo 'Error: ' . $_FILES['file']['error'] . '&lt;br&gt;';
  }
  else {
     if( move_uploaded_file($_FILES['file']['tmp_name'], 'uploads/' . $_FILES['file']['name']) ){
     echo "uploaded";
     }
     else{
     echo "not uploaded";
     }
  }
  
  ?&gt;
  </code></pre>
  
  <p>Please help to solve this problem.</p>