javascript promise in nested loop

Question

Im trying unsuccessfully to loop through an array that has an array as one of the params, I need to loop through that nested array in order to map it according to specs, then I need to run a function after the parent loop completes. Can someone point out my mistake on getting this accomplished?

const schedule = {}
data.schedule.forEach(item => {
  let date = moment(item.date).format('YYYY-MM-DD')
  let eventList = []
  item.events.forEach(event => {
    let start = moment(event.start).format('h:mm A')
    let end = moment(event.end).format('h:mm A')
    let time = `${start} - ${end}`
    eventList.push({time: time, name: event.name})
  })
  return Promise.all(eventList).then(list => {
    console.log('list', list)
    schedule[`${date}`] = list
  })
})

// this is my issue:

Promise.all(schedule).then(list => {
  console.log('schedule:', list)
})

// which bombs the method with:
// TypeError: (var)[Symbol.iterator] is not a function
// at Function.all (native)

I actually need to return an object that resembles this:

{'2017-12-06': [
  {time: '9am - 10am', name: 'Jackson Home'},
  {time: '11AM - 3PM', name: 'Jackson Home'},
  {time: '3PM - 8PM', name: 'Jackson Home'}
]}

`schedule` is an object, and cannot be iterated. See [this post](https://stackoverflow.com/questions/29292921/how-to-use-promise-all-with-an-object-as-input) or [this post](https://stackoverflow.com/questions/40732541/javascript-promises-iterate-over-all-object-keys-arrays-and-then-resolve). — Blue, Jan 23 '18 at 21:12
You don't need promises for what is shown....none of it is asynchronous. Provide some sample input data — charlietfl, Jan 23 '18 at 21:14
I just read about the array needed in a promise, which makes sense. — studiobrain, Jan 23 '18 at 21:19
`Promise.all` needs an array, but does your array need `Promise.all`? The answer is no. — trincot, Jan 23 '18 at 21:21

score 0 · Answer 1 · answered Jan 23 '18 at 21:21

Yep, Im an idiot and need to take a beverage break:

const schedule = {}

  data.schedule.forEach(item => {
    let date = moment(item.date).format('YYYY-MM-DD')
    let eventList = []
    schedule[`${date}`] = item.events.map(event => {
      let start = moment(event.start).format('h:mm A')
      let end = moment(event.end).format('h:mm A')
      let time = `${start} - ${end}`
      return {time: time, name: event.name}
    })
  })

  console.log('schedule:', schedule)

score 0 · Answer 2 · answered Jan 23 '18 at 21:23

As @charlietfl said, your code is not asynchronous, so you don't need Promise.

This code does what you needed:

const schedule = {}
data.schedule.forEach(item => {
  let date = moment(item.date).format('YYYY-MM-DD')
  let eventList = []
  item.events.forEach(event => {
    let start = moment(event.start).format('h:mm A')
    let end = moment(event.end).format('h:mm A')
    let time = `${start} - ${end}`
    eventList.push({time: time, name: event.name})
  })

  schedule[`${date}`] = eventList
})

For this input:

{
    schedule: [
        {
            date: '2017-01-01',
            events: [
                {
                    name: 'test',
                    start: '2017-01-01 10:00:00',
                    end: '2017-01-01 11:00:00'
                }
            ]
        }
    ]
}

... you get this:

{
    "2017-01-01": [
        {
            "time": "10:00 AM - 11:00 AM",
            "name": "test"
        }
    ]
}

javascript promise in nested loop

2 Answers2