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Compare two arrays of objects, and remove if object value is equal

I've tried modifying some of the similar solutions on here but I keep getting stuck, I believe I have part of this figured out however, the main caveat is that:
Some of the objects have extra keys, which renders my object comparison logic useless.
I am trying to compare two arrays of objects. One array is the original array, and the other array contains the items I want deleted from the original array. However there's one extra issue in that the second array contains extra keys, so my comparison logic doesn't work.
An example would make this easier, let's say I have the following two arrays:
const originalArray = [{id: 1, name: "darnell"}, {id: 2, name: "funboi"},
{id: 3, name: "jackson5"}, {id: 4, name: "zelensky"}];
const itemsToBeRemoved = [{id: 2, name: "funboi", extraProperty: "something"},
{id: 4, name: "zelensky", extraProperty: "somethingelse"}];
after running the logic, my final output should be this array:
[{id: 1, name: "darnell"}, {id: 3, name: "jackson5"}]
And here's the current code / logic that I have, which compares but doesn't handle the extra keys. How should I handle this? Thank you in advance.
const prepareArray = (arr) => {
return arr.map((el) => {
if (typeof el === "object" && el !== null) {
return JSON.stringify(el);
} else {
return el;
}
});
};
const convertJSON = (arr) => {
return arr.map((el) => {
return JSON.parse(el);
});
};
const compareArrays = (arr1, arr2) => {
const currentArray = [...prepareArray(arr1)];
const deletedItems = [...prepareArray(arr2)];
const compared = currentArray.filter((el) => deletedItems.indexOf(el) === -1);
return convertJSON(compared);
};

How about using filter and some? You can extend the filter condition on select properties using &&.
const originalArray = [
{ id: 1, name: 'darnell' },
{ id: 2, name: 'funboi' },
{ id: 3, name: 'jackson5' },
{ id: 4, name: 'zelensky' },
];
const itemsToBeRemoved = [
{ id: 2, name: 'funboi', extraProperty: 'something' },
{ id: 4, name: 'zelensky', extraProperty: 'somethingelse' },
];
console.log(
originalArray.filter(item => !itemsToBeRemoved.some(itemToBeRemoved => itemToBeRemoved.id === item.id))
)
Or you can generalise it as well.
const originalArray = [
{ id: 1, name: 'darnell' },
{ id: 2, name: 'funboi' },
{ id: 3, name: 'jackson5' },
{ id: 4, name: 'zelensky' },
];
const itemsToBeRemoved = [
{ id: 2, name: 'funboi', extraProperty: 'something' },
{ id: 4, name: 'zelensky', extraProperty: 'somethingelse' },
];
function filterIfSubset(originalArray, itemsToBeRemoved) {
const filteredArray = [];
for (let i = 0; i < originalArray.length; i++) {
let isSubset = false;
for (let j = 0; j < itemsToBeRemoved.length; j++) {
// check if whole object is a subset of the object in itemsToBeRemoved
if (Object.keys(originalArray[i]).every(key => originalArray[i][key] === itemsToBeRemoved[j][key])) {
isSubset = true;
}
}
if (!isSubset) {
filteredArray.push(originalArray[i]);
}
}
return filteredArray;
}
console.log(filterIfSubset(originalArray, itemsToBeRemoved));
Another simpler variation of the second approach:
const originalArray = [
{ id: 1, name: 'darnell' },
{ id: 2, name: 'funboi' },
{ id: 3, name: 'jackson5' },
{ id: 4, name: 'zelensky' },
];
const itemsToBeRemoved = [
{ id: 2, name: 'funboi', extraProperty: 'something' },
{ id: 4, name: 'zelensky', extraProperty: 'somethingelse' },
];
const removeSubsetObjectsIfExists = (originalArray, itemsToBeRemoved) => {
return originalArray.filter(item => {
const isSubset = itemsToBeRemoved.some(itemToBeRemoved => {
return Object.keys(item).every(key => {
return item[key] === itemToBeRemoved[key];
});
});
return !isSubset;
});
}
console.log(removeSubsetObjectsIfExists(originalArray, itemsToBeRemoved));

The example below is a reusable function, the third parameter is the key to which you compare values from both arrays.
Details are commented in example
const arr=[{id:1,name:"darnell"},{id:2,name:"funboi"},{id:3,name:"jackson5"},{id:4,name:"zelensky"}],del=[{id:2,name:"funboi",extraProperty:"something"},{id:4,name:"zelensky",extraProperty:"somethingelse"}];
/** Compare arrayA vs. delArray by a given key's value.
--- ex. key = 'id'
**/
function deleteByKey(arrayA, delArray, key) {
/* Get an array of only the values of the given key from delArray
--- ex. delList = [1, 2, 3, 4]
*/
const delList = delArray.map(obj => obj[key]);
/* On every object of arrayA compare delList values vs
current object's key's value
--- ex. current obj[id] = 2
--- [1, 2, 3, 4].includes(obj[id])
Any match returns an empty array and non-matches are returned
in it's own array.
--- ex. ? [] : [obj]
The final return is a flattened array of the non-matching objects
*/
return arrayA.flatMap(obj => delList.includes(obj[key]) ? [] : [obj]);
};
console.log(deleteByKey(arr, del, 'id'));

let ff = [{ id: 1, name: 'darnell' }, { id: 2, name: 'funboi' },
{ id: 3, name: 'jackson5' },
{ id: 4, name: 'zelensky' }]
let cc = [{ id: 2, name: 'funboi', extraProperty: 'something' },
{ id: 4, name: 'zelensky', extraProperty: 'somethingelse' }]
let ar = []
let out = []
const result = ff.filter(function(i){
ar.push(i.id)
cc.forEach(function(k){
out.push(k.id)
})
if(!out.includes(i.id)){
// console.log(i.id, i)
return i
}
})
console.log(result)

how to move elements in nested array of objects in javascript

I saw these two questions:
Javascript move objects in a nested
array
How to move element in nested
array
But they do not work for me.
So I have a nested dynamic array like this:
const data = [
{
id: 1,
subData: [
{
id: 2,
subData: []
},
{
id: 3,
subData: [
{
id: 4,
subData: []
}
]
}
]
},
{
id: 5,
subData: []
},
.
.
.
]
I have to move the nested elements with their "id". For example, how can I write a function that gives me the following result:
const data = [
{
id: 1,
subData: [
{
id: 2,
subData: []
},
{
id: 3,
subData: [] // object with id 4 was here
}
]
},
{
id: 5,
subData: []
},
{
id: 4, // now its here
subData: []
}
.
.
.
]
What I've tried so far is to write the following function to first find an element with a specific "id" and then move that object:
const findObjById = (obj, key, value) => {
if (obj[key] === value) {
return obj;
}
const keys = Object.keys(obj);
for (let i = 0; i < keys.length; i++) {
const k = keys[i];
if (obj[k] && typeof obj[k] === 'object') {
const found = findObjById(obj[k], key, value);
if (found) {
return found;
}
}
}
}
Works to find a specific object. But I could not move the found object

Here is an example using a generic traverse function which accepts a visitor callback which is run on each iteration of the traversal and based on the return value of the visitor either returns or continues. (see this answer for more discussion).
We can then create a splice_source traversal which accepts an object to traverse and a predicate to match by and returns the matched element after splicing it from its parent array, and a find_target_array which will return the subData array from an object that matches the passed predicate.
It only remains to push the retrieved source object to the retrieved target array.
This is just an example and will need error checking and streamlining for your particular use cases, but it illustrates some flexible techniques which may be useful moving forward.
const data = [{ id: 1, subData: [{ id: 2, subData: [], }, { id: 3, subData: [{ id: 4, subData: [], },], },], }, { id: 5, subData: [], },];
// generic 'traverse' which accepts a 'visitor' callback
function traverse(o, fn) {
for (const k in o) {
const res = fn.apply(this, [o, k]);
if (res) {
return res;
}
if (o[k] !== null && typeof o[k] == 'object') {
const res = traverse(o[k], fn);
if (res) return res;
}
}
}
// create custom 'visitors' to retrieve source and target arrays
const splice_source = (obj, predicate) =>
traverse(
obj,
// 'visitor' callback
(o, k) => {
let m_index = -1;
if (Array.isArray(o[k])) {
m_index = o[k].findIndex((o) => predicate(o, k));
}
return m_index !== -1 ? o[k].splice(m_index, 1)[0] : false;
});
const find_target_array = (obj, predicate) =>
traverse(
obj,
// 'visitor' callback
(o, k) => (predicate(o, k) ? o.subData : false)
);
// move {id: 4} to subData array of {id: 5}
const source_object = splice_source(data, (obj) => obj?.id === 4);
const target_array = find_target_array(data, (obj) => obj?.id === 5);
target_array.push(source_object);
console.log(JSON.stringify(data, null, 2));
// move {id: 3} to top level 'data' array
data.push(splice_source(data, (obj) => obj?.id === 3));
console.log(JSON.stringify(data, null, 2));
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Sort entire nested object by property in JavaScript

I would like to loop through a deeply nested object, and sort each level based on a property. In this case its id
Here's my object (there will me more levels, I just added 3 levels here for readability):
const myObj = [
{
id: 15,
children: [
{
id: 9,
children: [
{
id: 4,
children: []
},
{
id: 1,
children: []
}
]
},
{
id: 4,
children: [
{
id: 35,
children: [
{
id: 12,
children: []
},
{
id: 8,
children: []
}
]
},
{
id: 30,
children: [],
}
]
},
]
},
{
id: 2,
children: [
{
id: 9,
children: []
},
{
id: 3,
children: []
},
]
}
]
Here's the desired output:
const myObj = [
{
id: 2,
children: [
{
id: 3,
children: []
},
{
id: 9,
children: []
}
]
},
{
id: 15,
children: [
{
id: 4,
children: [
{
id: 30,
children: [],
},
{
id: 35,
children: [
{
id: 8,
children: []
},
{
id: 12,
children: []
}
]
},
]
},
{
id: 9,
children: [
{
id: 1,
children: []
},
{
id: 4,
children: []
}
]
},
]
}
]
And here's my attempt at sorting it:
const myObj = [{id:15,children:[{id:9,children:[{id:4,children:[]},{id:1,children:[]}]},{id:4,children:[{id:35,children:[{id:12,children:[]},{id:8,children:[]}]},{id:30,children:[],}]},]},{id:2,children:[{id:9,children:[]},{id:3,children:[]},]}]
function sortByOrderIndex(obj) {
obj.sort((a, b) => (a.orderindex > b.orderindex) ? 1 : ((b.orderindex > a.orderindex) ? -1 : 0));
return obj;
}
function sortNestedObj(obj) {
sortByOrderIndex(obj);
for (let i = 0; i < obj.length; i++) {
const t = obj[i];
if (t.children.length !== 0) {
sortNestedObj(t.children);
} else {
return;
}
}
}
console.log(sortByOrderIndex(myObj))
I've created a function that sorts an object, and then tried to create another object that loops through each object that has children and sort those children using the first function. And if those children have children, then sort those and so forth until a child has no children.

You could recursively sort the array and it's object's children like this:
const myObj = [{id:15,children:[{id:9,children:[{id:4,children:[]},{id:1,children:[]}]},{id:4,children:[{id:35,children:[{id:12,children:[]},{id:8,children:[]}]},{id:30,children:[],}]},]},{id:2,children:[{id:9,children:[]},{id:3,children:[]},]}]
function sortArray(array) {
array.sort((a, b) => a.id - b.id);
array.forEach(a => {
if (a.children && a.children.length > 0)
sortArray(a.children)
})
return array;
}
console.log(sortArray(myObj))

You can make a recursive sorting function:
const myObj = [{id:15,children:[{id:9,children:[{id:4,children:[]},{id:1,children:[]}]},{id:4,children:[{id:35,children:[{id:12,children:[]},{id:8,children:[]}]},{id:30,children:[],}]},]},{id:2,children:[{id:9,children:[]},{id:3,children:[]},]}]
const orderChildren = obj => {
obj.children.sort((a, b) => a.id - b.id);
if (obj.children.some(o => o.children.length)) {
obj.children.forEach(child => orderChildren(child));
}
return obj;
};
const myNewObj = myObj.map(o => orderChildren(o)).sort((a, b) => a.id - b.id);
console.log(myNewObj);
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You can do:
const myObj = [{id: 15,children: [{id: 9,children: [{id: 4,children: []},{id: 1,children: []}]},{id: 4,children: [{id: 35,children: [{id: 12,children: []},{id: 8,children: []}]},{id: 30,children: [],}]},]},{id: 2,children: [{id: 9,children: []},{id: 3,children: []},]}];
const deepSortById = arr => (arr.forEach(a => a.children && deepSortById(a.children)), arr.sort((a, b) => a.id - b.id));
const result = deepSortById(myObj);
console.log(result);
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I created generic solution for sorting nested arrays by id. My solution works with any nested array and sorts it according to id property. Or by any other property you specify in the method's seconds parameter.
function sortNestedArrays(obj, sortPropertyName) {
Object.keys(obj).forEach((key) => {
if (Array.isArray(obj[key])) {
obj[key].sort((a, b) => a[sortPropertyName] - b[sortPropertyName]);
}
if (!!obj[key] && (typeof obj[key] === 'object' || Array.isArray(obj[key]))) {
sortNestedArrays(obj[key], sortPropertyName);
}
});
return obj;
}
Usage is following:
obj = sortNestedArrays(obj, 'id');

Inserting nested properties from another object

I have two arraysmetaObjects and justObjects.
These Objects in both arrays have the id property in common.
I would like to create a new array that combines properties from the objects in the different arrays
const metaObjects = [
{
id: 1,
metaProp: "metaProp1"
},
{
id: 2,
metaProp: "metaProp2"
}
];
const justObjects = [
{
id: 1,
justProp: "justProp1"
},
{
id: 2,
justProp: "justProp2"
}
];
This is the outcome I expect
const result= [
{
id: 1,
metaProp: "metaProp1",
justProp: "justProp1"
},
{
id: 2,
metaProp: "metaProp2",
justProp: "justProp2"
}
];
I have tried to implement map of map to achieve this
const combinedObject = justObjects.map(_w => {
return metaObjects.map(_m => {
if (_w.id === _m.id) {
return { ..._m, ..._w };
}
});
}, metaObjects);
console.log(combinedObject);
But I get the following error
[ [ { id: 1, metaProp: 'metaProp1', justProp: 'justProp1' },
undefined ],
[ undefined,
{ id: 2, metaProp: 'metaProp2', justProp: 'justProp2' } ] ]
I am not sure why each array has an undefined in the inner arrays.
Also I need to flatten the arrays so that they are close to the expected results above.
I have heard about the composable lens functions of ramda
Could that be used here?

This is fairly similar to the answer from customcommander, but chooses to use groupBy and values rather than sortBy and groupWith. This feels more logical to me, especially avoiding an unnecessary sort call.
const {pipe, concat, groupBy, prop, values, map, mergeAll} = R
const joinOnId = pipe
( concat
, groupBy (prop ('id'))
, values
, map (mergeAll)
)
const metaObjects =
[ { id: 1, metaProp: "metaProp1" }
, { id: 2, metaProp: "metaProp2" }
, { id: 3, metaProp: "metaProp3" } // unique to `meta`
]
const justObjects =
[ { id: 1, justProp: "justProp1" }
, { id: 2, justProp: "justProp2" }
, { id: 4, justProp: "justProp4" } // unique to `just`
]
console.log
( joinOnId (metaObjects, justObjects)
)
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max-height: 100vh !important;
}
<script src="//cdnjs.cloudflare.com/ajax/libs/ramda/0.26.1/ramda.js"></script>
Note that this can easily be adjusted to accept different property name:
const joinOn = (propName) =>
pipe
( concat
, groupBy (prop (propName))
, values
, map (mergeAll)
)
// ...
const joinOnId = joinOn ('id')
or to use any common key-generation function:
const joinOn = (keyFn) =>
pipe
( concat
, groupBy (keyFn)
, values
, map (mergeAll)
)
// ...
const joinOnId = joinOn (prop ('id'))

You can search for the object to merge with find() and then use Object.assign() to merge them together. This assumes that the object already exists in metaObjects, if it doesn't you'll need to decide what to do in that case.
const metaObjects = [
{
id: 1,
metaProp: "metaProp1"
},
{
id: 2,
metaProp: "metaProp2"
}
];
const justObjects = [
{
id: 1,
justProp: "justProp1"
},
{
id: 2,
justProp: "justProp2"
}
];
justObjects.forEach(item => {
let toMerge = metaObjects.find(obj => obj.id === item.id)
Object.assign(toMerge, item)
})
console.log(metaObjects)
If metaObjects is potentially large, it would be better to store it as an object keyed to id. Then you could look it up directly without having to search each time.
If you don't want to alter metaObjects, you can map() over justObjects and create a new array:
const metaObjects = [
{
id: 1,
metaProp: "metaProp1"
},
{
id: 2,
metaProp: "metaProp2"
}
];
const justObjects = [
{
id: 1,
justProp: "justProp1"
},
{
id: 2,
justProp: "justProp2"
}
];
let newArray = justObjects.map(item => {
let toMerge = metaObjects.find(obj => obj.id === item.id)
return Object.assign({}, toMerge, item)
})
// metaObjects unaffected
console.log(newArray)

I think you could simply combine the two arrays together, group objects by id (you need to sort first) and finally merge each group:
const {
map,
mergeAll,
groupWith,
eqBy,
prop,
concat,
sortBy,
pipe
} = R;
const metaObjects = [
{ id: 1,
metaProp: "metaProp1" },
{ id: 2,
metaProp: "metaProp2" }];
const justObjects = [
{ id: 1,
justProp: "justProp1" },
{ id: 2,
justProp: "justProp2" }];
const process = pipe(
concat,
sortBy(prop('id')),
groupWith(eqBy(prop('id'))),
map(mergeAll));
console.log(
process(metaObjects, justObjects)
);
<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.26.1/ramda.min.js"></script>

I would use Array.prototype.reduce() or a for loop to convert one of them from an Array of objects with an id property to an object of objects, using the id as the key:
const merged = metaObjects.reduce((acc, cur) => {
acc[cur.id] = cur;
return acc;
}, {});
Or:
const merged = {};
for (const obj of metaObjects) {
merged[obj.id] = obj;
}
Then, iterate the other one while merging each of its entries in the object we have just created above:
justObjects.forEach((obj) => {
merged[obj.id] = Object.assign({}, merged[obj.id], obj);
});
Lastly, just convert it back to an Array using Object.values:
Object.values(merged);
Example:
const metaObjects = [{
id: 1,
metaProp: "metaProp1"
},{
id: 2,
metaProp: "metaProp2"
}];
const justObjects = [{
id: 1,
justProp: "justProp1"
},{
id: 2,
justProp: "justProp2"
},{
id: 3,
justProp: "justProp3"
}];
// Create an object of one of the two using is id property:
/*
// Alternative using reduce:
const merged = metaObjects.reduce((acc, cur) => {
acc[cur.id] = cur;
return acc;
}, {});
*/
// Alternative using a for loop:
const merged = {};
for (const obj of metaObjects) {
merged[obj.id] = obj;
}
// Iterate the other one and merge it with the map you have just created:
justObjects.forEach((obj) => {
merged[obj.id] = Object.assign({}, merged[obj.id], obj);
});
// Convert it back to an Array of objects:
console.log(Object.values(merged));
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max-height: 100vh !important;
}
Note this will work even if any of the two objects contain entries for an id that is not present in the other.

javascript find deeply nested objects

I need to filter objects recursively in a deeply nested array of objects using javascript, maybe with the help of lodash.
What is the cleanest way to do it, If I don't know how many nested object there will be in my array?
Let's say I have the following structure
[
{
label: "first",
id: 1,
children: []
},
{
label: "second",
id: 2,
children: [
{
label: "third",
id: 3,
children: [
{
label: "fifth",
id: 5,
children: []
},
{
label: "sixth",
id: 6,
children: [
{
label: "seventh",
id: 7,
children: []
}
]
}
]
},
{
label: "fourth",
id: 4,
children: []
}
]
}
];
I want to find the one with id 6, and if it has children return true otherwise false.
Of course If I have a similar data structure but with different number of items it should work too.

Since you only want a true of false answer you can use some() on the recursion, effectively doing a depth-first search, and make it pretty succinct:
let arr = [{label: "first",id: 1,children: []},{label: "second",id: 2,children: [{label: "third",id: 3,children: [{label: "fifth",id: 5,children: []},{label: "sixth",id: 6,children: [{label: "seventh",id: 7,children: []}]}]},{label: "fourth",id: 4,children: []}]}];
function findNested(arr, id) {
let found = arr.find(node => node.id === id)
return found
? found.children.length > 0
: arr.some((c) => findNested(c.children, id))
}
console.log(findNested(arr, 6)) // True: found with children
console.log(findNested(arr, 7)) // False: found no children
console.log(findNested(arr, 97)) // False: not found

Perhaps a recursive solution along the lines of this might work for you? Here, the node with supplied id is recursively searched for through the 'children' of the supplied input data. If a child node with matching id is found, a boolean result is returned based on the existence of data in that nodes children array:
function nodeWithIdHasChildren(children, id) {
for(const child of children) {
// If this child node matches supplied id, then check to see if
// it has data in it's children array and return true/false accordinly
if(child.id === id) {
if(Array.isArray(child.children) && child.children.length > 0) {
return true
}
else {
return false
}
}
else {
const result = nodeWithIdHasChildren(child.children, id);
// If result returned from this recursion branch is not undefined
// then assume it's true or false from a node matching the supplied
// id. Pass the return result up the call stack
if(result !== undefined) {
return result
}
}
}
}
const data = [
{
label: "first",
id: 1,
children: []
},
{
label: "second",
id: 2,
children: [
{
label: "third",
id: 3,
children: [
{
label: "fifth",
id: 5,
children: []
},
{
label: "sixth",
id: 6,
children: [
{
label: "seventh",
id: 7,
children: []
}
]
}
]
},
{
label: "fourth",
id: 4,
children: []
}
]
}
];
console.log('node 6 has children:', nodeWithIdHasChildren( data, 6 ) )
console.log('node 7 has children:', nodeWithIdHasChildren( data, 7 ) )
console.log('node 100 has children:', nodeWithIdHasChildren( data, 7 ), '(because node 100 does not exist)' )

Here is another solution using recursion and doing it via only one Array.find:
const data = [ { label: "first", id: 1, children: [] }, { label: "second", id: 2, children: [ { label: "third", id: 3, children: [ { label: "fifth", id: 5, children: [] }, { label: "sixth", id: 6, children: [ { label: "seventh", id: 7, children: [] } ] } ] }, { label: "fourth", id: 4, children: [] } ] } ];
const search = (data, id) => {
var f, s = (d, id) => d.find(x => x.id == id ? f = x : s(x.children, id))
s(data, id)
return f ? f.children.length > 0 : false
}
console.log(search(data, 6)) // True: found with children
console.log(search(data, 7)) // False: found but has no children
console.log(search(data, 15)) // False: not found at all
The idea is to have a recursive function which when finds the id remembers the object.
Once we have the found (or we know we do not have an entry found) just return the children array length or return false.
If you want to actually return the found object instead of the boolean for children.length:
const data = [ { label: "first", id: 1, children: [] }, { label: "second", id: 2, children: [ { label: "third", id: 3, children: [ { label: "fifth", id: 5, children: [] }, { label: "sixth", id: 6, children: [ { label: "seventh", id: 7, children: [] } ] } ] }, { label: "fourth", id: 4, children: [] } ] } ];
const search = (data, id) => {
var f, s = (d, id) => d.find(x => x.id == id ? f = x : s(x.children, id))
s(data, id)
return f
}
console.log(search(data, 6)) // returns only the object with id:6
console.log(search(data, 7)) // returns only the object with id: 7
console.log(search(data, 71)) // returns undefined since nothing was found

You can use "recursion" like below to check if id has children or not
let arr = [{label: "first",id: 1,children: []},{label: "second",id: 2,children: [{label: "third",id: 3,children: [{label: "fifth",id: 5,children: []},{label: "sixth",id: 6,children: [{label: "seventh",id: 7,children: []}]}]},{label: "fourth",id: 4,children: []}]}];
function hasChildren(arr, id) {
let res = false
for (let d of arr) {
if(d.id == id) return d.children.length > 0
res = res || hasChildren(d.children, id)
if(res) return true
}
return res
}
console.log('id 4 has children? ', hasChildren(arr, 4))
console.log('id 6 has children? ', hasChildren(arr, 6))

You can do it using three simple javascript functions:
// Function to Flatten results
var flattenAll = function(data) {
var result = [];
var flatten = function(arr) {
_.forEach(arr, function(a) {
result.push(a);
flatten(a.children);
});
};
flatten(data);
return result;
};
// Function to search on flattened array
var search = function(flattened, id) {
var found = _.find(flattened, function(d) {
return d.id == id;
});
return found;
};
// Function to check if element is found and have children
var hasChildren = function(element) {
return element && element.children && element.children.length > 0;
}
// Usage, search for id = 6
hasChildren(search(flattenAll(your_data_object), 6))
Plunker

You can use a generator function to iterate the nodes recursively and simplify your logic for checking existence by using Array.prototype.some():
const data = [{label:'first',id:1,children:[]},{label:'second',id:2,children:[{label:'third',id:3,children:[{label:'fifth',id:5,children:[]},{label:'sixth',id:6,children:[{label:'seventh',id:7,children:[]}]}]},{label:'fourth',id:4,children:[]}]}];
function * nodes (array) {
for (const node of array) {
yield node;
yield * nodes(node.children);
}
}
const array = Array.from(nodes(data));
console.log(array.some(node => node.id === 6 && node.children.length > 0));
console.log(array.some(node => node.id === 7 && node.children.length > 0));

The JSON.parse reviver parameter or the JSON.stringify replacer parameter can be used to check all values, and generate flat id lookup object with references to the nodes :
var lookup = {}, json = '[{"label":"first","id":1,"children":[]},{"label":"second","id":2,"children":[{"label":"third","id":3,"children":[{"label":"fifth","id":5,"children":[]},{"label":"sixth","id":6,"children":[{"label":"seventh","id":7,"children":[]}]}]},{"label":"fourth","id":4,"children":[]}]}]'
var result = JSON.parse(json, (key, val) => val.id ? lookup[val.id] = val : val);
console.log( 'id: 2, children count:', lookup[2].children.length )
console.log( 'id: 6, children count:', lookup[6].children.length )
console.log( lookup )

I suggest to use deepdash extension for lodash:
var id6HasChildren = _.filterDeep(obj,
function(value, key, parent) {
if (key == 'children' && parent.id == 6 && value.length) return true;
},
{ leavesOnly: false }
).length>0;
Here is a docs for filterDeep.
And this a full test for your case.

We now use object-scan for data processing needs like this. It's very powerful once you wrap your head around it. This is how you could solve your questions
// const objectScan = require('object-scan');
const hasChildren = (e) => e instanceof Object && Array.isArray(e.children) && e.children.length !== 0;
const find = (id, input) => {
const match = objectScan(['**'], {
abort: true,
rtn: 'value',
filterFn: ({ value }) => value.id === id
})(input);
return hasChildren(match);
};
const data = [{ label: 'first', id: 1, children: [] }, { label: 'second', id: 2, children: [{ label: 'third', id: 3, children: [{ label: 'fifth', id: 5, children: [] }, { label: 'sixth', id: 6, children: [{ label: 'seventh', id: 7, children: [] }] }] }, { label: 'fourth', id: 4, children: [] }] }];
console.log(find(6, data));
// => true
console.log(find(2, data));
// => true
console.log(find(7, data));
// => false
console.log(find(999, data));
// => false
.as-console-wrapper {max-height: 100% !important; top: 0}
<script src="https://bundle.run/object-scan#13.8.0"></script>
Disclaimer: I'm the author of object-scan