const my_arr = [
   {id: 1, arr: [{subId: 1, value: 1}],
   {id: 2, arr: [{subId: 2, value: 2}],
   {id: 3, arr: [{subId: 3, value: 1}],
]

how do I map over this array my_arr and then map over arr to return an array like so:

[
  {subId: 1, value: 1},
  {subId: 3, value: 1},
]

basically filtering out only where values are 1 and then returning only that sub object

I’ve tried doing

my_arr.map((x) => x.map((y) => y.value === 1 ? y : null)) 

>Solution :

You can try this approach with flatMap and filter

const my_arr = [
   {id: 1, arr: [{subId: 1, value: 1}]},
   {id: 2, arr: [{subId: 2, value: 2}]},
   {id: 3, arr: [{subId: 3, value: 1}]},
]

const result = my_arr.flatMap(item => item.arr).filter(item => item.value === 1)

console.log(result)