I found that running the npm install command in the same directory where your Angular project is, eliminates these warnings. I do not know the reason why.
Specifically, I was trying to use ng2-completer
$ npm install ng2-completer --save
npm WARN saveError ENOENT: no such file or directory, open 'C:\Work\foo\package.json'
npm notice created a lockfile as package-lock.json. You should commit this file.
npm WARN enoent ENOENT: no such file or directory, open 'C:\Work\foo\package.json'
npm WARN [email protected] requires a peer of @angular/common@>= 6.0.0 but none is installed. You must install peer dependencies yourself.
npm WARN [email protected] requires a peer of @angular/core@>= 6.0.0 but noneis installed. You must install peer dependencies yourself.
npm WARN [email protected] requires a peer of @angular/forms@>= 6.0.0 but none is installed. You must install peer dependencies yourself.
npm WARN foo No description
npm WARN foo No repository field.
npm WARN foo No README data
npm WARN foo No license field.
I was unable to compile. When I tried again, this time in my Angular project directory which was in foo/foo_app, it worked fine.
cd foo/foo_app
$ npm install ng2-completer --save