As for the downloads, I think there's already npm local cache handling this.
And I am not sure if I understand correctly what you want to achieve, but you can create and intermediate dependency that would aggregate common libraries and then use its build output in your other projects. Maybe it would be a good use case to define the "vendor.js/css" files.
Something like Specific project -> Common Module -> [vendor1, vendor2,...]
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As for the downloads, I think there's already npm local cache handling this.
And I am not sure if I understand correctly what you want to achieve, but you can create and intermediate dependency that would aggregate common libraries and then use its build output in your other projects. Maybe it would be a good use case to define the "vendor.js/css" files.
Something like
Specific project -> Common Module -> [vendor1, vendor2,...]