Document Previews in Browser

You'll want to integrate a cross-browser cross-type document viewer. Google will give you some good sites, personally I've had good experiences with Flex Paper.

For demos, see here: http://flexpaper.devaldi.com/demo/

There is another approach that can be used to view images/pdf/xlsx/docx etc.

You can use iframe and google's gview in the following way:

 const YOUR_URL = https://calibre-ebook.com/downloads/demos/demo.docx;
 
 <iframe
   className="doc"
   src={`https://docs.google.com/gview?url=${YOUR_URL}&embedded=true`}
 />

There is the Javascript ViewerJs. An open source tool which allows a website to display PDF and open standard for office documents. It will display the documents inline and without browser plugins.