The serve command requires to be run in an Angular project, but a project definition could not be found.

2018/12/8 Angular

The serve command requires to be run in an Angular project, but a project definition could not be found.

ng serveとコマンドを打つと、「The serve command requires to be run in an Angular project, but a project definition could not be found.」とエラーが出たのでなんでだろう、と思っていると、package.jsonと同じディレクトリでコマンドを打っていなかったから出ていたようです。