Broken behaviour in JS codegen

jscodegen.nim

# broken in js
var frontier = newHeap[FrontierElem[Tile, float32]](frontiercmp) do (a, b: FrontierElem[Tile, float32]) -> int:
 return cmp(a.priority, b.priority)
 
# error:
Uncaught ReferenceError: colonanonymouse__223267 is not defined
however it works correctly when compiled to C.

# workaround for js
proc frontiercmp(a,b: FrontierElem[Tile, float32]): int =
  return cmp(a.priority, b.priority)
var frontier = newHeap[FrontierElem[Tile, float32]](frontiercmp)