[mediaqueries] Add issue on the definition of scripting:initial-only

Author: frivoal

mediaqueries/Overview.bs

@@ -1906,6 +1906,36 @@ scripting</h3>
 			that render a page on a server
 			and send a nearly-static version of the page to the user.
 
+			Issue: Should there be an explicit minimum threshold to meet
+			before a UA is allowed to claim ''initial-only''?
+			Having one would mean authors would know
+			what they can depend on,
+			and could tailor their scripts accordingly.
+			On the other hand, pinpointing that threshold is difficult:
+			if it is set too low,
+			the scripting facilities that authors can depend on
+			may be to constrained to be practical,
+			even though actual UAs may potentially
+			all support significantly more.
+			But trying to set it higher may cause us to exclude
+			UAs that do support scripting at loading time,
+			but restrict it in some cases based on complex heuristics.
+			For instance, conservative definitions likely include at least
+			running all inline scripts and firing the DOMContentLoaded event.
+			But it does not seem useful for authors to constrain themselves to this
+			if most (or maybe all) ''initial-only'' UAs
+			also load external scripts (including ''async'' and ''defer'')
+			and fire the load event.
+			On the other hand,
+			requiring external scripts to be loaded
+			and the load event to be fired
+			could exclude UAs like Opera mini,
+			which typically do run them,
+			but may decide not to based on timeouts and other heuristics.
+			
+			
+			
+
 		<dt><dfn>none</dfn>
 		<dd>
 			Indicates that the user agent will not run scripts for this document;