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How to get immediate parent Id of the child id in array of nested json Object?

I need to get the parent id of the specific child.
Here is my sample JSON, If I give entity id 32 it should return 6 as parent Id and if I give 30 it should return 5 as parent id.
const arr = [{
"id": 0,
"name": "My Entity",
"children": [
{
"id": 1,
"name": "MARKET",
"children": [
{
"id": 2,
"name": "Sales",
"children": [
{
"id": 3,
"name": "District 1",
"children": [
{
"id": 5,
"name": "Area 1",
"children": [
{
"entityId": 30,
"id": 26,
"name": "Mumbai"
},
{
"entityId": 31,
"id": 26,
"name": "Hyderabad"
}
],
"num": 0,
},
{
"id": 6,
"name": "Area 2",
"children": [
{
"entityId": 32,
"id": 32,
"name": "Karnataka"
},
{
"entityId": 33,
"id": 33,
"name": "Andhra Pradesh"
}
],
"num": 0,
},
]
},
]
},
]
},
]
}]
Here is the code I have tried
const findParent = (arr, entityId) => {
for (let i = 0; i < arr.length; i++) {
if (arr[i].entityId === entityId) {
return [];
} else if (arr[i].children && arr[i].children.length) {
const t = findParents(arr[i].children, entityId);
if (t !== false) {
t.push(arr[i].id);
return t;
}
}
}
return false;
};
findParents(arr, 30);
But it is returning like below
[
5,
3,
2,
1,
0
]
But I want the output to be
[
5
]
Kindly help me on this, thanks

Replace this:
t.push(arr[i].id);
with:
if (t.length == 0) t.push(arr[i].id);

I would suggest easier solution
const findParent = (arr, entityId) => {
const children = arr.flatMap(parent =>
(item.children || []).map(child => ({ parent, child, entityId: child.entityId }))
)
const res = children.find(item => item.entityId === entityId)
return res.entityId || findChildren(res.map(v => v.child), entityId)
}

copying data from one array to another array

Array One:
array1 = [{
"id": 1,
"name": "aaaaa",
"attr": [{"attr_code": "a_id", "value": "5"}]
},
{
"id": 2,
"name": "bbbbb",
"attr": [{"attr": "a_id", "value": "4"}]
}]
Array Two:
array2 = [{
"id": 4,
"name": "bef",
},
{
"id": 5,
"name": "bcd",
}]
Resulting Array:
resultingArray = [{
"id": 1,
"name": "aaaaa",
"attr": [{"attr_code": "a_id", "value": "5"}],
"a_id" : {"id": 5, "name": "bcd"}
},
{
"id": 2,
"name": "bbbbb",
"attr": [{"attr": "a_id", "value": "4"}],
"a_id" : {"id": 4, "name": "bef"}
}]
I am looking to add the array2 objects into array1 based on id's of array2. I have tried using map function on both the arrays to compare and add the object but I didn't succeed. Can you please suggest me how to do it?
Thank you

Add the array2 objects into array1 based on ids of array2.
let array1 =
[
{
"id": 1,
"name": "aaaaa",
"attr": [{"attr_code": "a_id", "value": "5"}]
},
{
"id": 2,
"name": "bbbbb",
"attr": [{"attr": "a_id", "value": "4"}]
}
];
let array2 = [{
"id": 4,
"name": "bef",
},
{
"id": 5,
"name": "bcd",
}
];
let resultingArray=[];
array1.forEach(function(element) {
element['a_id'] = [];
element['attr'].forEach(function(attr) {
element['a_id'].push(array2.find(function(item) {
return item.id == attr.value;
}));
});
resultingArray.push(element)
});
console.log(resultingArray);

I presume you intend to extract the object whose ID is equal to the value field the in the each object in array1.
var array1 = [{
"id": 1,
"name": "aaaaa",
"attr": [{"attr_code": "a_id", "value": "5"}]
},
{
"id": 2,
"name": "bbbbb",
"attr": [{"attr": "a_id", "value": "4"}]
}];
var array2 = [{
"id": 4,
"name": "bef",
},
{
"id": 5,
"name": "bcd",
}];
var resultingArray = [];
for(var i = 0; i < array1.length; i++) {
resultingArray[i] = array1[i];
for(var j = 0; j < array2.length; j++) {
if(resultingArray[i].attr[0].attr_code.value === array2[j].id) {
resultingArray[i].push("a_id": array2[j]);
}
}
}
You just need to lop through array1, and for each object in array1, you need to find corresponding objects in array2 which match the criterion.

You can use array map and array index to do:
var array1 = [{
"id": 1,
"name": "aaaaa",
"attr": [{"attr_code": "a_id", "value": "5"}]
},
{
"id": 2,
"name": "bbbbb",
"attr": [{"attr": "a_id", "value": "4"}]
}];
var array2 = [{
"id": 4,
"name": "bef",
},
{
"id": 5,
"name": "bcd",
}];
var result = array1.map(current=>{
//find index of attr in array2
let index = array2.findIndex(c=>{
if (c['id']===(Number(current['attr'][0]['value'])))
return c;
});
current["a_id"] = array2[index];
return current;
});
console.log(result);

Please check if the following code suites your requirement. You may need to make some changes.
function mergeArrays3 (arr1, arr2) {
return arr1.map((value, index) => {
let object = null;
let result = {...value};
for (let element of arr2) {
if (element.id == parseInt(value.attr[0].value)) {
object = element;
break;
}
}
if (object != null) {
let attr = value.attr[0];
if (attr.hasOwnProperty("attr")) {
result[value.attr[0].attr] = object;
} else if (attr.hasOwnProperty("attr_code")) {
result[value.attr[0].attr_code] = object;
}
}
return result;
});
}
I loop over first array and find an element in second array matching id of value.attr[0].value. If found then i added this object in the first array at key of value.attr[0].attr or value.attr[0].attr_code.

I have tried using map function on both the arrays to compare and add
the object but I didn't succeed
Below is the functional programming approach using map():
/* GIVEN */
const array1 = [{
"id": 1,
"name": "aaaaa",
"attr": [{
"attr_code": "a_id",
"value": "5"
}]
},
{
"id": 2,
"name": "bbbbb",
"attr": [{
"attr": "a_id",
"value": "4"
}]
}
]
const array2 = [{
"id": 4,
"name": "bef",
},
{
"id": 5,
"name": "bcd",
}]
/* From array2, make an object keyed by the 'id' field. We'll use this as a key-value lookup table */
const lookupTable = array2.reduce((accum, item) => {
accum[item.id.toString()] = item
return accum
}, {})
console.log('***LOOKUP TABLE***\n', lookupTable) // result is an object we use to lookup
/* From array1, we append data from the lookup table */
const final = array1.map(item => {
item.a_id = lookupTable[item.attr[0].value]
return item
})
console.log("***RESULT***\n", final)
Hope this helps.
Cheers,

Sorting JSON alphabetically by first letter

I have a JSON like this:
[
{
"id": 1,
"slug": "abakan",
"name": "Абакан"
},
{
"id": 4,
"slug": "almetevsk",
"name": "Альметьевск"
},
{
"id": 10,
"slug": "astrahan",
"name": "Астрахань"
},
{
"id": 11,
"slug": "barnaul",
"name": "Барнаул"
},
...
]
And getting this by this method:
public function getCities()
{
$cities = City::mainCities()->get(['id', 'slug', 'name']);
return response()->json($cities);
}
How can i sort this list alphabetically and with their letters. For example:
"A": [
{
"id": 1,
"slug": "abakan",
"name": "Абакан"
},
{
"id": 4,
"slug": "almetevsk",
"name": "Альметьевск"
}
],
"B": [
{
"id": 11,
"slug": "barnaul",
"name": "Барнаул"
},
...
]
and so on...
I have Laravel on the backend and VueJS on front.

My solution:
var cities = [
{ id: 1, slug: "abakan", name: "Абакан" },
{ id: 4, slug: "almetevsk", name: "Альметьевск" },
{ id: 11, slug: "barnaul", name: "Барнаул" },
{ id: 10, slug: "astrahan", name: "Астрахань" }
];
cities.sort(function(a, b) {
return a.slug[0].localeCompare(b.slug[0]);
});
var newCities = {};
for (var i = 0; i < cities.length; i++) {
var c = cities[i].slug[0].toUpperCase();
if (newCities[c] && newCities[c].length >= 0)
newCities[c].push(cities[i]);
else {
newCities[c] = [];
newCities[c].push(cities[i]);
}
}
console.log(newCities);

This works for me:
var items = [
{
"id": 11,
"slug": "barnaul",
"name": "Барнаул"
},
{
"id": 1,
"slug": "abakan",
"name": "Абакан"
},
{
"id": 4,
"slug": "almetevsk",
"name": "Альметьевск"
},
{
"id": 10,
"slug": "astrahan",
"name": "Астрахань"
}
];
var sortedItems = items.sort((a, b) => a.slug.localeCompare(b.slug));
var results = {};
for (var i = 0; i < 26; i++) {
var char = String.fromCharCode(97 + i);
var bigChar = char.toUpperCase();
results[bigChar] = [];
for (var s = 0; s < sortedItems.length; s++) {
if (sortedItems[s].slug.startsWith(char)) {
results[bigChar].push(sortedItems[s]);
}
}
}
console.log(results)

Javascript get data totals into list

I have this data:
{
"id": "123",
"name": "name here",
"thsub": {
"637": {
"id": "637",
"name": "Sub 1",
"stats": {
"items": 5,
},
"ons": null
},
"638": {
"id": "638",
"name": "Sub 2",
"stats": {
"items": 10,
},
"ons": null
}
},
"ph": 10,
}
Here's is the code:
mydata = [mydata];
var chList=[];
var thList=[];
var thCount=[];
for (var i = 0; i < mydata.length; i++) {
var obj = mydata[i];
var cl = obj.name;
if (obj.thsub != null) {
chList.push(cl);
}
if(obj.thsub) {
if (i < 10) {
var nme = Object.keys(obj.thsub).map( function(key){
var item = obj.thsub[key];
return item.name;
});
thCount.push(numberofitems);
thList = thList.concat(nme);
thCount = thCount.concat(Array(nme.length).fill(nme.length));
}
}
}
My problem is in the thCount ... what I need to do is to count each "items" on obj.thsub.638 or other ...stats.items and put the totals into thCount like I've got in thList.
So the desired result woule be 5 and 10 in other words: [5, 10] in this case.
thCount would be [5, 10]
How can I do this?

you should access the json objects using key value, index is for arrays. below code just does the thcount for you
var data = {
"id": "123",
"name": "name here",
"thsub": {
"637": {
"id": "637",
"name": "Sub 1",
"stats": {
"items": 5,
},
"ons": null
},
"638": {
"id": "638",
"name": "Sub 2",
"stats": {
"items": 10,
},
"ons": null
}
},
"ph": 10,
};
var thCount = [];
for(key in data.thsub ){
if(data.thsub[key].stats){
thCount.push(data.thsub[key].stats.items);
}
}
console.log(thCount);

Object.values gives you the list of values of a given object and then you can map your result in an array. in ES5:
var arr = Object.values(mydata.thsub).map(function(item) {
return item.stats.items
});
in ES6:
const list = Object.values(mydata.thsub).map(item => item.stats.items);

You could use an iterative recursive approach for getting the wanted values.
function getValues(object, key) {
function iter(o) {
if (key in o) {
result.push(o[key]);
}
Object.keys(o).forEach(function (k) {
if (o[k] && typeof o[k] === 'object') {
iter(o[k]);
}
});
}
var result = [];
iter(object);
return result;
}
var data = { id: "123", name: "name here", thsub: { 637: { id: "637", name: "Sub 1", stats: { items: 5, }, ons: null }, 638: { id: "638", name: "Sub 2", stats: { items: 10, }, ons: null } }, ph: 10, };
console.log(getValues(data, 'items'));
.as-console-wrapper { max-height: 100% !important; top: 0; }

Making one to many relation array in JavaScript

I have two arrays of objects:
var a = [{
"id": 1,
"name": "q"
},
{
"id": 2,
"name": "l"
}]
and another is
var b = [{
"id": 3,
"sub": 1,
"name": "ni"
},
{
"id": 4,
"sub": 2,
"name": "bh"
}]
Here sub is the id in a
I need to have a new array which will look like this:
var c = [
{
"id":1,
"name":"q",
"map":[
{
"id":3,
"name":"ni"
}
]
},
{
"id":2,
"name":"l",
"map":[
{
"id":4,
"name":"bh"
}
]
}
]
How can I do that in JavaScript?
I am using underscore in my project.

In plain Javascript you could use Array#map, Array#forEach and a hash table.
var a = [{ "id": 1, "name": "q" }, { "id": 2, "name": "l" }],
b = [{ "id": 3, "sub": 1, "name": "ni" }, { "id": 4, "sub": 2, "name": "bh" }],
hash = Object.create(null),
result = a.map(function (a, i) {
hash[a.id] = { id: a.id, name: a.name };
return hash[a.id];
}, hash);
b.forEach(function (a) {
hash[a.sub].map = hash[a.sub].map || [];
hash[a.sub].map.push({ id: a.id, name: a.name });
}, hash);
console.log(result);
ES6
var a = [{ "id": 1, "name": "q" }, { "id": 2, "name": "l" }],
b = [{ "id": 3, "sub": 1, "name": "ni" }, { "id": 4, "sub": 2, "name": "bh" }],
hash = Object.create(null),
result = a.map((hash => a => hash[a.id] = { id: a.id, name: a.name, map: [] })(hash));
b.forEach((hash => a => hash[a.sub].map.push({ id: a.id, name: a.name }))(hash));
console.log(result);

You can do it with the help of map function and then use the find function to search the data from the other array.
var b = [{
"id": 3,
"sub": 1,
"name": "ni"
}, {
"id": 4,
"sub": 2,
"name": "bh"
}];
var a = [{
"id": 1,
"name": "q"
}, {
"id": 2,
"name": "l"
}];
var final = _.map(b, function(d) {
return {
id: d.name,
name: d.name,
map: _.find(a, function(adata) {
return adata.id == d.sub; //use underscore find to get the relevant data from array a
})
}
});
console.log(final);
<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore-min.js"></script>