Is Tableau Javascript API available for Tableau Online?

I have a website which will be used to show dashboards created in Tableau Desktop and published in Tableau Online.

I wanted to use Tableau Javascript API to access the dashboard to show it to users, but I don't want my web users to login to Tableau online.

My question is simply that "Can Tableau Javascript API be used to login to Tableau Online in the background and then fetch dashboards/views from it..?"

Based on my reading of the authentication documentation, there are three options:

1. Tableau Public requires no authentication for users to see visualizations. Tradeoffs: visualizations are static and public, and your storage space is limited. Ref: this forum discussion.
2. Tableau Online requires user login.
3. Tableau Server requires user login, unless you configure it to say that requests from your web server are always from trusted users. (See Trusted Authentication.) But even then, I think the license agreement requires that they be licensed users. You can license Tableau Server by # of cores instead of # of users though, in which case Tableau Server allows you to set up a Guest user that can access views anonymously.

So the short answer to your question appears to be no, not with Tableau Online. You have other options, but you either have to live with Public's limits or you'll need your own server, running Tableau Server. Even then you'd need to pay for each user to be licensed to access the product, unless you purchase a license based on # of cores, not # of users.