Lexical scoping in a for loop enclosing a promise?

Question

I have an ids object, which maps id strings to product objects.

for id of ids
  product = ids[id]
  console.log product #          


        

Answer 1

Bergi's code is misleading IMO since it runs the whole loop at once, not sequentially. For that reason I would just lift all the code to work in promises instead of mixing sync and async:

Promise.resolve(product for _, product of ids).then next = (products) ->
  [product, products...] = products
  if product
    console.log product
    Product.create(product).then ->
      console.log product
      next products
.then ->
  console.log "all done"

The difference is:

• Like in a real loop, next item won't run until the previous has completed
• Like in a real loop, the next line (just needs a then -> runs only after the loop has completed completely

These properties of a real loop are much more important than superficial syntax which you can learn in a couple of days.

Let it run and look at the difference in the logs.