formsubmit-ajax.js

var $form = $('#your-form');

$form.on('submit', function(evt){
  evt.preventDefault();
  
  $.ajax({
    url: $form.attr('action'),
    type: $form.attr('method'),
    data: $form.serialize(),
    success: function(data){
        // do shit with your data
    }
  });
});

// OR an easier way

$form.submit(function(data){
  // do shit with your data
});