When you see the module installed by --save, it will be displayed in dependencies.
And the modules in dependencies represent the dependencies of the production environment. Such as jQuery.

But what I don’t understand is, take jQuery as an example. Why should I declare dependencies in dependencies?
In a production environment, I will directly use script tags to reference jQuery, without dependencies at all. What happens if the modules that the production environment depends on are declared in dependencies? Will it automatically add script tags for me or, for example, when packaging modules, when packaging production environment modules, will all dependencies in dependencies be packaged? But as far as I know, for example, when webpack modules are packaged, they are packaged based on the dependency graph created by the require module, so I don't quite understand why production environment dependencies should be declared in dependencies.