JS map inside map

Question

I have the following code which works but I was looking for a cleaner solution:

  const routeLists = solution.vehicle_list[0].route_list

  const solutionMarkers = routeLists.map((el: any) => (
    {
      latitude: el.source_latitude,
      longitude: el.source_longitude,
      type: el.route_type
    }
  ))

  const customerMarkers = routeLists.map((el: any) => {
    return el.destinations_list.map((el: any) => {
      return {
        latitude: el.latitude,
        longitude: el.longitude,
        type: 'customer'
      }
    })
  }).map((el: MarkerType, i: number) => el[i])

  const markers = [...solutionMarkers, ...customerMarkers]

route_list sample data:

...
      "route_list": [
        {
          "route_id": "dc Truck 231 Route #1",
          "route_type": "dc",
          "sequence_number": 0,
          "source_id": 0,
          "source_latitude": 33.87,
          "source_longitude": -123.87,
          "planned_start": "2012-04-23T18:25:43.511Z",
          "planned_end": "2012-04-23T18:25:43.511Z",
          "activity_list": [
            {
              "sequence_number": 0,
              "type": "loading",
              "planned_start": "2012-04-23T18:25:43.511Z",
              "planned_end": "2012-04-23T18:25:43.511Z",
              "planned_duration": 0
            }
          ],
          "destinations_list": [
            {
              "destination_id": 0,
              "sequence_number": 0,
              "address": "string",
              "latitude": 33.87,
              "longitude": -118.34,
              "planned_arrival": "2012-04-23T18:25:43.511Z",
              "order_id": 0,
              "time_window_start": "2012-04-23T18:25:43.511Z",
              "time_window_end": "2012-04-23T18:25:43.511Z"
            }
          ]
        }
      ]
...

is there a way to map on routeLists only once? I have tried to use concat within customerMarkers but I didn't make it to work yet

Answer 1

You can use reduce, like this:

const markers = routeLists.reduce((acc, rec) => {
  let result = [{
    latitude: rec.source_latitude,
    longitude: rec.source_longitude,
    type: rec.route_type
  }]
  if (typeof rec.destinations_list !== 'undefined' && rec.destinations_list.length) {
    return [...acc, ...result, ...(rec.destinations_list.map((el: any) => {
      return {
        latitude: el.latitude,
        longitude: el.longitude,
        type: 'customer'
      }
    }))]
  }
  return [...acc, ...result]
}, [])

Answer 2

You can use reduce then nest destinations list in it:

const markers = routeLists.reduce((accum, current) => {
    accum.push({
        latitude: current.source_latitude,
        longitude: current.source_longitude,
        type: current.route_type
    });
    current.destinations_list.forEach(el => {
        accum.push({
            latitude: el.latitude,
            longitude: el.longitude,
            type: "customer"
        });
    });
    return accum;
}, []);