visa

No, you will not need a visa because you are allowed to stay in Shanghai for up to 144 hours based on 144 hour visa free transit rule, if you don't have any additional stop within mainland China, of course. I assume that you intend to fly on QV866 from Shanghai to Laos, right?

The most important detail is that you declare in US, at check-in your real intention and this is:

US - Shanghai - Laos

You will present the printouts of your flight tickets and after a short inspection, you will be allowed to board the plane.

Upon your arrival in Shanghai, you will approach 144 hour visa free transit counter where you will fill out a blue form. Shortly after, you will be allowed to exit the airport.