Deep Flatten JavaScript Object Recursively

Question

Data:

var data = [
    {
      \"id\": 1,
      \"level\": \"1\",
      \"text\": \"Sammy\",
      \"type\": \"Item\",
      \"items\": [
               


        

Answer 1

Since this older question has been brought back up, here is a modern version. It does not mutate (@Nina Scholz: or mutilate!) the original data, but returns a new array containing new objects.

const flattenItems = (xs) =>
  xs. flatMap (({items, ... node}) => [node, ... flattenItems (items || [])])

const data = [{id: 1, level: "1", text: "Sammy", type: "Item", items: [{id: 11, level: "2", text: "Table", type: "Item", items: [{id: 111, level: "3", text: "Dog", type: "Item", items: null}, {id: 112, level: "3", text: "Cat", type: "Item", items: null}]}, {id: 12, level: "2", text: "Chair", type: "Item", items: [{id: 121, level: "3", text: "Dog", type: "Item", items: null}, {id: 122, level: "3", text: "Cat", type: "Item", items: null}]}]}, {id: 2, level: "1", text: "Sundy", type: "Item", items: [{id: 21, level: "2", text: "MTable", type: "Item", items: [{id: 211, level: "3", text: "MTDog", type: "Item", items: null}, {id: 212, level: "3", text: "MTCat", type: "Item", items: null}]}, {id: 22, level: "2", text: "MChair", type: "Item", items: [{id: 221, level: "3", text: "MCDog", type: "Item", items: null}, {id: 222, level: "3", text: "MCCat", type: "Item", items: null}]}]}, {id: 3, level: "1", text: "Bruce", type: "Folder", items: [{id: 31, level: "2", text: "BTable", type: "Item", items: [{id: 311, level: "3", text: "BTDog", type: "Item", items: null}, {id: 312, level: "3", text: "BTCat", type: "Item", items: null}]}, {id: 32, level: "2", text: "Chair", type: "Item", items: [{id: 321, level: "3", text: "BCDog", type: "Item", items: null}, {id: 322, level: "3", text: "BCCat", type: "Item", items: null}]}]}]

console .log (flattenItems (data))

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This version does not include the fairly useless items property. It would be easy enough to add it in, with something like this:

const flattenItems = (xs) =>
  xs. flatMap (({items, ... node}) => [
    {... node, items: items == null ? null : []}, 
    ... flattenItems (items || [])
  ])