show file as image

Question

I am developing a site with Node js, it has functionality to upload/download files like (pdf, slide, docx, etc.). And able to show the files that were uploaded. Now I have a problem showing it in the view (wanted it shows the image of the 1st page of the file in the view) example as on the slideshare site. Someone could give a caplittle? I’ve tried searching but I can’t find it. Thank you.