How to upload image, pdf and display with react and express?

I am building a react app with express server. I need to upload images and pdf's. After uploaded they need to be displayed in web pages. The original plan was to upload to mongodb as Buffer type or with gridfs. But I could not find a way to display images or pdfs with buffer in mongodb? Is there a way to display with buffer and pdf with buffer? Or I should rather store files on server?