Difference in browser windows that can and can't have tabs

Question

I'm constrained to code (JavaScript, HTML) I can edit in a new window created by a window.open(URL, target, specs) function. I cannot change the opener window in any way.

I'm trying to open links in a way that makes sense - either in a new tab in the current window or a new window, depending on browser settings. But I can't do it.

All I can do is:

• <a href=URL target="_blank"> opens in a new tab in the original window, causing user disorientation,
• window.open(URL, name) opens like the above,
• window.open(URL, name, specs) opens another browser window, giving the user 3 windows to manage.

Ideally, the opener would do something sensible like honor the user preference for opening links in their choice of a new tab or a new window, bit this won't be achievable.

I've noticed a browser window that can't have tabs to be ones created with JavaScript's window.open(URL, name, specs) function and those that can have tabs to be window.open(URL, name), omitting the specs argument.

I'm struggling to understand how browser windows that have tabs differ from those that can't have tabs.

Definitely looking to learn from the community! Thanks for any thoughts.