After you download and extract a pre-built distribution library from GitHub, you find two folders: build and web. PDF.js library files can be found in build folder where as web folder contains a viewer project that incudes viewer.html, viewer.css, viewer.js and related files. If you check viewer.html code, you can see that it references pdf.js library from build folder and other relat... https://products.documentprocessing.com/viewer/javascript/pdf.js/