get id by value in hierarcial data with js

Question

I have hierarcial data as tree array:

var myData = [
    {
      id: 0,
      title:"Item 1"
    }, {
      id: 1,
      title:"Item 2",
      subs: [
        {
          id: 10,
          title:"Item 2-1",
          subs: [
        {
          id: 100,
          title:"Item 2-2-1"
        }, {
          id: 110,
          title:"Item 2-2-2"
        }, {
          id: 120,
          title:"Item 2-2-3"
        }
      ]
        }, {
          id: 11,
          title:"Item 2-2"
        }, {
          id: 12,
          title:"Item 2-3"
        }
      ]
    }, {
      id: 2,
      title:"Item 3"
    },
    // more data here
];

I need to get id by title in this array. I try to use this function:

console.log(myData.findIndex(item=>item.title==="Item 3"))

But it works bad for "Item 2-2". How should I solve this problem?

Do subitems possibly have indefinite subitems?

holydragon
– holydragon

2022-06-30 10:16:18 +00:00
Commented Jun 30, 2022 at 10:16 — holydragon
– holydragon, Commented Jun 30, 2022 at 10:16
yes,they are. subitems possibly have indefinite subitems

Владимир Кузовкин
– Владимир Кузовкин

2022-07-02 14:12:54 +00:00
Commented Jul 2, 2022 at 14:12 — Владимир Кузовкин
– Владимир Кузовкин, Commented Jul 2, 2022 at 14:12

Doc · Accepted Answer · 2022-07-03 10:09:34Z

1

I made this simple findId method in order to find the title and returns the id or undefined as result made for your data array structure.

findId(title, list) function. Its purpose is to iterate the list received in the second parameter, look for the title in each element and if there is a match it returns the id, otherwise it checks if there are subs in the element and in that case it is called recursively the findId function using the subs of the element as a list. If an element is found, its id is returned, otherwise the iteration continues.

This will work fine, assuming each title is unique in the array.
Otherwise only the first will be found.

Take a look at the following

function findId(title, list) {
  for (const _item of list) {
    if (_item.title === title) {
      // Return some top-level id
      return _item.id;
      
    // If the item is not the one, check if it has subs
    } else if (_item?.subs) { 
    
      // Use _item.subs as a list, calling the function recursively
      const subId = findId(title, _item.subs);
      
      // Return some nested subId if found
      if (subId !== undefined) return subId;
    }
  }
  // Return undefined if not found
  return undefined;
}


var myData = [
{
    id: 0,
    title: "Item 1"
  }, 
  {
    id: 1,
    title: "Item 2",
    subs: [
    {
      id: 10,
      title: "Item 2-1",
      subs: [
      {
        id: 100,
        title: "Item 2-2-1"
      }, {
        id: 110,
        title: "Item 2-2-2"
      }, {
        id: 120,
        title: "Item 2-2-3"
      }]
    }, {
      id: 11,
      title: "Item 2-2"
    }, {
      id: 12,
      title: "Item 2-3"
    }]
  }, 
  {
    id: 2,
    title: "Item 3"
  },
  // more data here
];

console.log("Id: ", findId("Item 2", myData));
console.log("Id: ", findId("Item 2-1", myData));
console.log("Id: ", findId("Item 2-2-2", myData));
console.log("Id: ", findId("Wrong Title", myData));

console.log("Id: ", findId("Item 2", myData));<br/>
console.log("Id: ", findId("Item 2-1", myData));<br/>
console.log("Id: ", findId("Item 2-2-2", myData));<br/>
console.log("Id: ", findId("Wrong Title", myData));<br/>

The last one returns undefined as intended, since the title is not included in the array.

edited Jul 3, 2022 at 10:09

answered Jun 30, 2022 at 10:23

Doc

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6 Comments

Владимир Кузовкин Over a year ago

It doesn't work well with

Doc Over a year ago

What do you mean? Why? It's working in the snippet, also for the subs items.

Владимир Кузовкин Over a year ago

console.log("Id: ", findId("Item 2-2-3")) shows undefined

Doc Over a year ago

There is no element with that title. What result would you expect? EDIT Oh, you update your array... Let me update the one in my post.

Владимир Кузовкин Over a year ago

It would be great. Thank you!!

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