If you're interested in non-Javascript time travel debugging: pernos.co (which is layered over Mozilla's rr time-tracking debugger) is an absolutely amazing tool which will save you days and days of wasted development time.
Pernosco's tool is described pretty well on their website, but basically it allows you to view a program inside and out, forwards /and/ backwards, with zero replay lag. Everything from stack traces to variable displays (at any point in time in your code execution) is extremely easy to view and understand. The best part is the lightning fast search functionality (again: zero lag).
On top of this: extraordinary customer service if anything breaks (in my experience, they fix bugs within 24 hours and are highly communicative).
Pernosco's tool is described pretty well on their website, but basically it allows you to view a program inside and out, forwards /and/ backwards, with zero replay lag. Everything from stack traces to variable displays (at any point in time in your code execution) is extremely easy to view and understand. The best part is the lightning fast search functionality (again: zero lag).
On top of this: extraordinary customer service if anything breaks (in my experience, they fix bugs within 24 hours and are highly communicative).