You must select either a code-first or a Sitecore-first development workflow. Some application modes only apply to a specific development workflow.
During development, you can use the following modes:
Disconnected mode - does not require a running Sitecore instance. You host the application in your local environment, and you use local content data. Use this mode if you opted for the code-first development workflow.
Connected mode - requires a running Sitecore instance. You host the application in your local environment, and you use content data from your Sitecore instance.
Integrated mode - requires a running Sitecore instance, which hosts the application, provides content data, and renders your application server-side.
In production, you can run a JSS application using one of the following modes: