Resolve an array of JS promises one after another - one liner

resolve-promise-array-ordered.js

// Example data.
const data = [1, 2, 3]
const fn = async a => a * a

// If we care about errors.
data.reduce((carry, item) => carry.then(() => fn(item)), Promise.resolve())
  .catch(console.error)
  .then(() => { ... })

// If we don't care.
data.reduce((carry, item) => carry.then(() => fn(item), () => {}), Promise.resolve())
  .then(() => { ... })

// You can also pass the argument around.
data.reduce((carry, item) => carry.then(res => fn(res + item)), Promise.resolve(1))
  .then(res => { ... })