When you are on a cell in Command mode(blue color mode), simply press Shift + DownArrow or Shift + UpArrow to select multiple cells. Press ctrl + C. And that’s it. You have copied your entire selected code at once. It doesn’t affect whether you have cell outputs.
Command mode: The Jupyter Notebook has two different keyboard input modes. Edit mode allows you to type code or text into a cell and is indicated by a green cell border. Command mode binds the keyboard to notebook level commands and is indicated by a grey cell border with a blue left margin.