Travelling with Visa expiring but I-797 Approved

[dparekh]

Hi,

My H1 B Visa is expiring on my passport on 12/11/2017 but I have an approved I-797 till 12/11/2020.

I am planning to travel to Canada for 3-4 days in first week of December.

So when I come back do I get a I94 based on my approved I-797 (12/11/2020) or till 12/11/2017 as on my Visa on my passport.

Do I need to get my passport stamped before I travel to Canada.

Thanks for all the help.