ern add <packages..>--dev/-ddevDependencies--peer/-ppeerDependencies--manifestId <manifestId>ern add <packages..> command is the ern equivalent of yarn add and npm install When you work with a MiniApp, always use ern add to add packages in place of yarn add or npm install.npm or yarn) to be used by this command to add the package. This can be done by adding or updating packageManager field in the ern object kept in the MiniApp package.json. For example, to use npm. If this field is missing from the configuration, yarn will be used over npm if it is installed on the workstation.ern add <packages..> command performs compatibility checks before adding the package to the project.ern add as the version to use will be retrieved from the Manifest. If you add an explicit version for a package, it will be ignored.ern add <packages> command performs the following checks:ern installs the package at the version declared in the manifest.