How can I pass a variable parameter name of a button using ajax?

See more:

PHP

Ajax

I want to pass a name parameter of a button using AJAX POST method to a PHP file.

I am getting an error after submitting the form with Ajax that the index is undefined on the page 2.

What I have tried:

The HTML form:

<form class="upVote" action=""  method="post">
<button id="plus" name="plus" value="foo">button</button>
</form>';

The AJAX:

$(document).ready(function(){
  $(".upVote").submit(function(){
      $.ajax({
          url: "../inc/handlers/up-vote.php",
          data: $(".upVote").serialize(),
          type: "POST",
          dataType: 'json',
          success: function (e) {
              console.log(JSON.stringify(e));
          },
          error:function(e){
              console.log(JSON.stringify(e));
              console.log('error');
          }
      });
      return false;
  });
});

The PHP POST:

$_POST['plus'];