Pdfjs is an open source PDF reader, which uses the rendering engine of WebKit kernel to parse and present PDF files. The working principle of pdfjs is to render the contents of PDF to the parser and then to the canvas for display, so the PDF file we render with pdfjs is actually a canvas picture.

In PDFjs, there are two ways to load pdf files: loadFile () and renderPage (). The loadFile () method is used to load a PDF file, while the renderPage () method is used to render a single page in a PDF file. When using pdfjs, we need to call the loadFile () method to load the PDF file, and then call the renderPage () method to render each page.