An index directory can contain a specified directory or exclude a specified directory or file by folder or file name. For example, the front-end project contains the html and js files that I need, and also contains the node_modules directory, but I don’t need the node_modules directory. This directory can be in any folder and exists for each project, so if adding it manually would be a lot of work, it would be convenient to exclude this directory directly by using the folder name node_modules.