How to find a object in a nested array using recursion in JS

Question

Consider the following deeply nested array:

const array = [
    {
        id: 1,
        name: "bla",
        children: [
            {
                id: 23,
                name: "bla",
                children: [{ id: 88, name: "bla" }, { id: 99, name: "bla" }]
            },
            { id: 43, name: "bla" },
            {
                id: 45,
                name: "bla",
                children: [{ id: 43, name: "bla" }, { id: 46, name: "bla" }]
            }
        ]
    },
    {
        id: 12,
        name: "bla",
        children: [
            {
                id: 232,
                name: "bla",
                children: [{ id: 848, name: "bla" }, { id: 959, name: "bla" }]
            },
            { id: 433, name: "bla" },
            {
                id: 445,
                name: "bla",
                children: [
                    { id: 443, name: "bla" },
                    {
                        id: 456,
                        name: "bla",
                        children: [
                            {
                                id: 97,
                                name: "bla"
                            },
                            {
                                id: 56,
                                name: "bla"
                            }
                        ]
                    }
                ]
            }
        ]
    },
    {
        id: 15,
        name: "bla",
        children: [
            {
                id: 263,
                name: "bla",
                children: [{ id: 868, name: "bla" }, { id: 979, name: "bla" }]
            },
            { id: 483, name: "bla" },
            {
                id: 445,
                name: "bla",
                children: [{ id: 423, name: "bla" }, { id: 436, name: "bla" }]
            }
        ]
    }
];

How would I grab a certain object by key that might be deeply nested, using recursion? I have tried this, but this won't work for nesting deeper than 2 levels, it then just returns undefined:

const findItemNested = (arr, itemId, nestingKey) => {
    for (const i of arr) {
        console.log(i.id);
        if (i.id === itemId) {
            return i;
        }
        if (i[nestingKey]) {
            findItemNested(i[nestingKey], itemId, nestingKey);
        }
    }
};

The result should be:

const res = findItemNested(array, 959, "children"); >> { id: 959, name: "bla" }

This can perhaps also be achieved using .find, or just to flatten the array (by the children key), but using recursion seems like the most logical solution to me. Does anybody have a solution to this?

Thanks in advance :).

Answer 1

You might use a recursive reduce:

const array=[{id:1,name:"bla",children:[{id:23,name:"bla",children:[{id:88,name:"bla"},{id:99,name:"bla"}]},{id:43,name:"bla"},{id:45,name:"bla",children:[{id:43,name:"bla"},{id:46,name:"bla"}]}]},{id:12,name:"bla",children:[{id:232,name:"bla",children:[{id:848,name:"bla"},{id:959,name:"bla"}]},{id:433,name:"bla"},{id:445,name:"bla",children:[{id:443,name:"bla"},{id:456,name:"bla",children:[{id:97,name:"bla"},{id:56,name:"bla"}]}]}]},{id:15,name:"bla",children:[{id:263,name:"bla",children:[{id:868,name:"bla"},{id:979,name:"bla"}]},{id:483,name:"bla"},{id:445,name:"bla",children:[{id:423,name:"bla"},{id:436,name:"bla"}]}]}];

const findItemNested = (arr, itemId, nestingKey) => (
  arr.reduce((a, item) => {
    if (a) return a;
    if (item.id === itemId) return item;
    if (item[nestingKey]) return findItemNested(item[nestingKey], itemId, nestingKey)
  }, null)
);
const res = findItemNested(array, 959, "children");
console.log(res);