Creating a promise chain in a for loop

Question

I would expect the code below to print one number on the console, then wait a second and then print another number. Instead, it prints all 10 numbers immediately and then wa

Answer 1

You have to assign the return value of .then back to chain:

chain = chain.then(()=>getProm(i))
         .then(Wait)

Now you will basically be doing

chain
  .then(()=>getProm(1))
  .then(Wait)
  .then(()=>getProm(2))
  .then(Wait)
  .then(()=>getProm(3))
  .then(Wait)
  // ...

instead of

chain
  .then(()=>getProm(1))
  .then(Wait)

chain
  .then(()=>getProm(2))
  .then(Wait)

chain
  .then(()=>getProm(3))
  .then(Wait)
// ...

You can see that the first one is actually a chain, while the second one is parallel.