Detecting visibility of element in viewport

element_extensions.rb

module Watir
  class Element
    def on_screen?
      windowHeight = browser.execute_script('return window.innerHeight')
      elementRect = browser.execute_script('return arguments[0].getBoundingClientRect()', self)
      elementTop = elementRect["top"]

      return elementTop >= 0 && elementTop < windowHeight
    end
  end
end