Cucumber step to manually trigger javascript events in Selenium scenarios (using jQuery)

When you cannot make Selenium trigger events you rely on (e.g. a "change" event when filling in a form field), trigger it yourself using this step:

When /^I manually trigger a (".*?") event on (".*?")$/ do |event, selector|
  page.execute_script("jQuery(#{selector}).trigger(#{event})")
end

Note that this only triggers events that were registered through jQuery. Events registered through CSS or the native Javascript registry will not trigger.