serializing the form in Prototype with correct submit button

gistfile1.js

var currentSubmit = null

form.select('input[type=submit]').invoke('observe', 'click', function(e) {
  currentSubmit = this.name
})

form.observe('submit', function(e) {
  var params = this.serialize({ submit: currentSubmit })
  console.log(Object.inspect(params))
})