using map with filter array JavaScript

October 10, 2022

i have a json and need to extract data to array.

const data = [{
  "week": 1,
  "lost": 10,
  "recovery_timespan": [{
    "week": 2,
    "count": 1
  }, {
    "week": 3,
    "count": 0
  }],
   "netLost": 10,
  "netReturned": 20
}, {
  "week": 2,
  "lost": 7,
  "recovery_timespan": [{
    "week": 3,
    "count": 1
  }],
  "netLost": 30,
  "netReturned": 200
}, {
  "week": 3,
  "lost": 8,
  "recovery_timespan":"",
  "netLost": 50,
  "netReturned": 40
}];

Expected output: lost,count in recovery_timespan,netLost , netReturned.

[ [ 10, 1, 0, 10, 20 ], [ 7, 1, 30, 200 ], [ 8, 50, 40 ] ]

As you can see expected output, last recovery_timespan does not contain any data and it just shows as "".so i need to ignore it.

My approach:

const result = data.map(({lost, recovery_timespan,netLost,netReturned}) => [
  lost,
  ...recovery_timespan.map(({count}) => count),
  netLost,netReturned
]);

My code breaks when "recovery_timespan" is "". How can i add a filter along with map to filter that part and make my code work?

>Solution :

It’s just a matter of checking if it’s string or not, but you can short circuit

const result = data.map(({lost, recovery_timespan,netLost,netReturned}) => [
  lost,
  ...(recovery_timespan || []).map(({count}) => count),
  netLost,netReturned
]);