Still, the title is disappointing because switching to a type checked dialect of JS won't fix the bloat issues that are fundamental to the browser as a platform.
There may be a case that typed languages ship with fewer initial defects in new features but I'm not entirely convinced it's always competitive with the return in development speed and simplified testing you can get staying untyped. Particularly when your underlying problem is not CPU bound.
Solo project or very small team then? When everyone understands all code?
Of course it's faster to go type less then.
Add 4 more people and you'll end up debugging runtime errors because it was intuitive what you should send to $COLLEAGUE's functions but in reality they expect something else.
Or at best, $COLLEAGUE will document the type info in comments :)