Assign a CB Auto Action to one specific page?

How do I write inline javascript early in the head of one specific page.
I assume I should use a CB Auto Action of:

• type: code
• trigger: onBeforeCompileHead
• Method: javascript(inline). 

But there's no way (that I can see) to assign such an action to one specific page? 

Hacked workround: I have used the above approach, but wrapped my code in an 'if' that matches the path of the specific page. But this surely can't be the proper approach, because it adds the code to every page, including backend pages.
 

I'd suggest just using CB Content Module instead. You can then assign it to your menu item. CB Content Module can output JavaScript, jQuery, and CSS in addition to regular content.

If there isn't a menu item to assign to or you still want to use onBeforeCompileHead then you'd need to add a condition to check for the URL. You can substitute in URL parameters using [get_PARAMETER] as well for easy access to parameter checks. PHP conditions can also be used to use Joomla API to retrieve the current URL and do checks against it however you need.

More haste, less speed. Please read the question more carefully.

...early in the head

I have plenty of ways to add javascript to the body. However, unless it's in the head, users see the original page, then a flash to a new page (because the script does a redirect after encoding an extra attribute in the URL).

I ... wrapped my code in an 'if' ... But this surely can't be the proper approach

So, telling me "you'd need to add a condition" is what I've already done, and the question was asking how it should be done without a condition.

If it can't be done with CB, pls just say.