Do you have a windows store JavaScript/HTML applications that needs performance tuning? 

PerfView can handle JavaScript.    In particular

  1. It automatically collects the necessary events so that it can decode the names of the JavaScript functions on any stacks that are captured.  (Note however that if your JavaScript has been obfuscated, you do have problem). 
  2. When you use the Memory->Take HeapSnapshot command on a process that has a JavaScript heap it will dump that heap (it will also dump the .NET heap if it has that (or both)). 

For the most part, investigations of JavaScript applications are basically the same as that for .NET.  The main differences is in the heap dumping.   Because JavaScript objects don't have a 'type' basically what PerfView can't aggregate as much (normally it aggregates by type), and what it shows instead is object property names (in .NET it shows the type names and NOT the property/field names).   The basic strategy however is the same, so the PerfView videos are pretty relevant.   

Vance

I have a note to myself to beef up the documentation in this regard, and well as do some targeted videos, but it may be a while