Requires photo-collage, which requires node-canvas. I forked photo-collage because it wasn't building on the latest Node.js (12+). That's why photo-collage is loaded from joeyguerra/photo-collage.git#master. Also, you'll have to install node-canvas. If you do it on Mac using brew install pkg-config cairo pango libpng jpeg giflib librsvg, you'll likely have to set the PKG_CONFIG_PATH so the Cairo build can find libffi.
PKG_CONFIG_PATH="/usr/local/opt/libffi/lib/pkgconfig/" npm iRun it like:
PHOTOS_PATH=/Users/you/yourfoldertoabunchofphotos node index.js