Focus on the PDF Viewer When It Loads

To focus on the PSPDFKit instance when it loads, get a reference to the window object of the PSPDFKit for Web viewer frame and call focus() on it after the PSPDFKit.load promise resolves:

PSPDFKit.load(configuration).then((instance) => {

This has been tested with PSPDFKit for Web 2020.5.1.