Develop Reference

Transformation of nested object

I am new to JavaScript and Node JS
want to transform the following nested object with student
Data:
[{
"id": 1,
"name": "A",
"children": [{
"id": 2,
"name": "B",
"children": [{
"id": 3,
"name": "C"
},
{
"id": 4,
"name": "D"
}
]
}]
}]
to
Expected:
[{
"student": {
"id": 1,
"name": "A"
},
"children": [{
"student": {
"id": 2,
"name": "B"
},
"children": [{
"student": {
"id": 3,
"name": "C"
}
},
{
"student": {
"id": 4,
"name": "D"
}
}
]
}]
}]

I guess you are seeking a solution for an array with multiple student objects. So you can use the map method to modify them.
const original = [{
"id": 1,
"name": "A",
"children": [{
"id": 2,
"name": "B",
"children": [{
"id": 3,
"name": "C"
},
{
"id": 4,
"name": "D"
}
]
}]
}]
const modified = original.map(stu => {
return {
student: {
id: stu.id,
name: stu.name,
},
children: stu.children
}
})

Change Array to Object with recursives

i have an array shared below. I need to change this array like an object. I tried something but cant make it. I Want to make like this with foreach or recursive functions.
let nodes= [
{ id: 1, name: "Denny Curtis", title: "CEO", img: "https://cdn.balkan.app/shared/2.jpg" },
{ id: 2, pid: 1, name: "Ashley Barnett", title: "Sales Manager", img: "https://cdn.balkan.app/shared/3.jpg" },
{ id: 3, pid: 1, name: "Caden Ellison", title: "Dev Manager", img: "https://cdn.balkan.app/shared/4.jpg" }
];
let newObj = {
"id": 1,
"name": "Denny Curtis",
"title": "CEO",
"img": "https://cdn.balkan.app/shared/2.jpg",
"children": [
{
"id": 2,
"pid": 1,
"name": "Ashley Barnett",
"title": "Sales Manager",
"img": "https://cdn.balkan.app/shared/3.jpg",
"children": [
{
"id": 4,
"pid": 2,
"name": "Elliot Patel",
"title": "Sales",
"img": "https://cdn.balkan.app/shared/5.jpg"
},
{
"id": 5,
"pid": 2,
"name": "Lynn Hussain",
"title": "Sales",
"img": "https://cdn.balkan.app/shared/6.jpg"
}
]
}
]
}
Thank you from now.

It would probably be better to make an array of users with the children related to them.
let nodes = [{
id: 1,
name: "Denny Curtis",
title: "CEO",
img: "https://cdn.balkan.app/shared/2.jpg"
},
{
id: 2,
pid: 1,
name: "Ashley Barnett",
title: "Sales Manager",
img: "https://cdn.balkan.app/shared/3.jpg"
},
{
id: 3,
pid: 1,
name: "Caden Ellison",
title: "Dev Manager",
img: "https://cdn.balkan.app/shared/4.jpg"
}
];
let newNodeArray = [];
nodes.forEach(node=>{
newNodeArray.push({...node,children: nodes.filter(filterNode => filterNode.pid === node.id )});
});
console.log(JSON.stringify(newNodeArray));
The outcome of this one would look like:
[
{
"id":1,
"name":"Denny Curtis",
"title":"CEO",
"img":"https://cdn.balkan.app/shared/2.jpg",
"children":[
{
"id":2,
"pid":1,
"name":"Ashley Barnett",
"title":"Sales Manager",
"img":"https://cdn.balkan.app/shared/3.jpg"
},
{
"id":3,
"pid":1,
"name":"Caden Ellison",
"title":"Dev Manager",
"img":"https://cdn.balkan.app/shared/4.jpg"
}
]
},
{
"id":2,
"pid":1,
"name":"Ashley Barnett",
"title":"Sales Manager",
"img":"https://cdn.balkan.app/shared/3.jpg",
"children":[]
},
{
"id":3,
"pid":1,
"name":"Caden Ellison",
"title":"Dev Manager",
"img":"https://cdn.balkan.app/shared/4.jpg",
"children":[]
}
]
//This is how you would do it if you want the response to be an object
let nodeObject = {...nodes.filter(node=>!node.pid)[0],children:[]};
nodeObject.children = nodes.filter(node=>nodeObject.id === node.pid);
nodeObject.children = nodeObject.children.map(node=>({...node,children: nodes.filter(filterNode=>node.id === filterNode.pid)}));
console.log(nodeObject);
// The Response for this would be:
{
"id": 1,
"name": "Denny Curtis",
"title": "CEO",
"img": "https://cdn.balkan.app/shared/2.jpg",
"children": [{
"id": 2,
"pid": 1,
"name": "Ashley Barnett",
"title": "Sales Manager",
"img": "https://cdn.balkan.app/shared/3.jpg",
"children": [{
"id": 4,
"pid": 2,
"name": "Caden Ellison",
"title": "Sales",
"img": "https://cdn.balkan.app/shared/4.jpg"
}]
}, {
"id": 3,
"pid": 1,
"name": "Caden Ellison",
"title": "Dev Manager",
"img": "https://cdn.balkan.app/shared/4.jpg",
"children": []
}]
}

How to filter through children of array of objects and then return parent with updated children?

I'm trying to filter through an array of objects it's children then update the children and return the parent with updated children.
Example array of objects:
[
{
"id": 1,
"name": "group1",
"users": [
{
"id": 1,
"name": "Mike"
},
{
"id": 2,
"name": "Steve"
},
{
"id": 3,
"name": "John"
}
]
},
{
"id": 2,
"name": "group2",
"users": [
{
"id": 4,
"name": "Phill"
},
{
"id": 5,
"name": "Joe"
},
{
"id": 6,
"name": "Dominik"
}
]
}
]
I've got an input in React where someone can type in a name of an user, then i'd like to only show the users with that name while keeping the group that they're in.
For example, if the input is 'Mike' I would like the result to be:
[
{
"id": 1,
"name": "group1",
"users": [
{
"id": 1,
"name": "Mike"
}
]
},
{
"id": 2,
"name": "group2",
"users": []
}
]

You can use map() and filter() to do that.
let arr = [ { "id": 1, "name": "group1", "users": [ { "id": 1, "name": "Mike" }, { "id": 2, "name": "Steve" }, { "id": 3, "name": "John" } ] }, { "id": 2, "name": "group2", "users": [ { "id": 4, "name": "Phill" }, { "id": 5, "name": "Joe" }, { "id": 6, "name": "Dominik" } ] } ];
function filterUsers(arr, name) {
return arr.map(obj => {
return {
...obj,
"users": obj.users.filter(user => user.name === name)
};
});
}
console.log(filterUsers(arr, "Mike"));

How do I flatten a (forest of) trees?

I have a forest of trees of arbitrary height, more or less like this:
let data = [
{ "id": 2, "name": "AAA", "parent_id": null, "short_name": "A" },
{
"id": 10, "name": "BBB", "parent_id": null, "short_name": "B", "children": [
{
"id": 3, "name": "CCC", "parent_id": 10, "short_name": "C", "children": [
{ "id": 6, "name": "DDD", "parent_id": 3, "short_name": "D" },
{ "id": 5, "name": "EEE", "parent_id": 3, "short_name": "E" }
]
},
{
"id": 4, "name": "FFF", "parent_id": 10, "short_name": "F", "children": [
{ "id": 7, "name": "GGG", "parent_id": 4, "short_name": "G" },
{ "id": 8, "name": "HHH", "parent_id": 4, "short_name": "H" }
]
}]
}
];
And I'm trying to produce a representation of all the root-to-leaves paths, something like this
[
[
{
"id": 2,
"name": "AAA"
}
],
[
{
"id": 10,
"name": "B"
},
{
"id": 3,
"name": "C"
},
{
"id": 6,
"name": "DDD"
}
],
[
{
"id": 10,
"name": "B"
},
{
"id": 3,
"name": "C"
},
{
"id": 5,
"name": "EEE"
}
],
[
{
"id": 10,
"name": "B"
},
{
"id": 4,
"name": "F"
},
{
"id": 7,
"name": "GGG"
}
],
[
{
"id": 10,
"name": "B"
},
{
"id": 4,
"name": "F"
},
{
"id": 8,
"name": "HHH"
}
]
]
So I wrote the following code:
function flattenTree(node, path = []) {
if (node.children) {
return node.children.map(child => flattenTree(child, [...path, child]));
} else {
let prefix = path.slice(0, path.length - 1).map(n => ({ id: n.id, name: n.short_name }));
let last = path[path.length - 1];
return [...prefix, { id: last.id, name: last.name } ];
}
}
let paths = data.map(n => flattenTree(n, [n]));
but paths comes out with extra nesting, like this:
[
[
{
"id": 2,
"name": "AAA"
}
],
[
[
[
{
"id": 10,
"name": "B"
},
{
"id": 3,
"name": "C"
},
{
"id": 6,
"name": "DDD"
}
],
[
{
"id": 10,
"name": "B"
},
{
"id": 3,
"name": "C"
},
{
"id": 5,
"name": "EEE"
}
]
],
[
[
{
"id": 10,
"name": "B"
},
{
"id": 4,
"name": "F"
},
{
"id": 7,
"name": "GGG"
}
],
[
{
"id": 10,
"name": "B"
},
{
"id": 4,
"name": "F"
},
{
"id": 8,
"name": "HHH"
}
]
]
]
]
I lost count of the many ways in which I tried to fix this, but it does look like the algorithm should not produce the extra nesting -- or my eyes are just so crossed by now that I couldn't see my mistake if someone stuck their finger on it.
Can someone help? Feel free to peruse this JSFiddle https://jsfiddle.net/png7x9bh/66/

The extra nestings are created by map. map just wraps the results into an array and returns them, it doesn't care if it is called on child nodes or not. Use reduce and just concat (or push, whatever suits your performance) the results into the first level array directly:
let data = [{"id":2,"name":"AAA","parent_id":null,"short_name":"A"},{"id":10,"name":"BBB","parent_id":null,"short_name":"B","children":[{"id":3,"name":"CCC","parent_id":10,"short_name":"C","children":[{"id":6,"name":"DDD","parent_id":3,"short_name":"D"},{"id":5,"name":"EEE","parent_id":3,"short_name":"E"}]},{"id":4,"name":"FFF","parent_id":10,"short_name":"F","children":[{"id":7,"name":"GGG","parent_id":4,"short_name":"G"},{"id":8,"name":"HHH","parent_id":4,"short_name":"H"}]}]}];
function flattenTree(node, path = []) {
let pathCopy = Array.from(path);
pathCopy.push({id: node.id, name: node.name});
if(node.children) {
return node.children.reduce((acc, child) => acc.concat(flattenTree(child, pathCopy)), []);
}
return [pathCopy];
}
let result = data.reduce((result, node) => result.concat(flattenTree(node)), []);
console.log(JSON.stringify(result, null, 3));

How to collect value in javascript?

I have an array like this in Javascript. Something like this
[
{
"id": 1,
"facilities": [
{
"id": 10,
"name": "Wifi",
"label": "Wifi"
},
{
"id": 12,
"name": "Toll",
"label": "Toll"
}
]
},
{
"id": 2,
"facilities": [
{
"id": 10,
"name": "Wifi",
"label": "Wifi"
},
{
"id": 12,
"name": "Toll",
"label": "Toll"
},
{
"id": 13,
"name": "Snack",
"label": "Snack"
}
]
},
{
"id": 3,
"facilities": [
{
"id": 10,
"name": "Wifi",
"label": "Wifi"
},
{
"id": 12,
"name": "Toll",
"label": "Toll"
},
{
"id": 14,
"name": "Petrol",
"label": "Petrol"
}
]
}
]
I want to collect data and grouping data facilities of the array in Javascript, something like this.
"facilities": [
{
"id": 10,
"name": "Wifi",
"label": "Wifi"
},
{
"id": 12,
"name": "Toll",
"label": "Toll"
},
{
"id": 13,
"name": "Snack",
"label": "Snack"
},
{
"id": 14,
"name": "Petrol",
"label": "Petrol"
}
]
So, basically, group by facilities. I just don't know how to handle the grouping of similar facilities values.

Assuming the facility ids are unique:
const facilities = input.reduce((memo, entry) => {
entry.facilities.forEach((f) => {
if (!memo.some((m) => m.id === f.id)) {
memo.push(f)
}
})
return memo
}, [])

You can iterate through all rows and collect (id, entity) map.
Index map allows us to not search already collected entities every time.
Then you can convert it to an array with object keys mapping.
let input = [
{"id": 1, "facilities": [{"id": 10, "name": "Wifi", "label": "Wifi"}, {"id": 12, "name": "Toll", "label": "Toll"} ] },
{"id": 2, "facilities": [{"id": 10, "name": "Wifi", "label": "Wifi"}, {"id": 12, "name": "Toll", "label": "Toll"}, {"id": 13, "name": "Snack", "label": "Snack"} ] },
{"id": 3, "facilities": [{"id": 10, "name": "Wifi", "label": "Wifi"}, {"id": 12, "name": "Toll", "label": "Toll"}, {"id": 14, "name": "Petrol", "label": "Petrol"} ] }
];
let index = input.reduce((res, row) => {
row.facilities.forEach(f => res[f.id] = f);
return res;
}, {});
let result = Object.keys(index).map(id => index[id]);
console.log({facilities: result});

You could use a Set for flagging inserted objects with the given id.
var data = [{ id: 1, facilities: [{ id: 10, name: "Wifi", label: "Wifi" }, { id: 12, name: "Toll", label: "Toll" }] }, { id: 2, facilities: [{ id: 10, name: "Wifi", label: "Wifi" }, { id: 12, name: "Toll", label: "Toll" }, { id: 13, name: "Snack", label: "Snack" }] }, { id: 3, facilities: [{ id: 10, name: "Wifi", label: "Wifi" }, { id: 12, name: "Toll", label: "Toll" }, { id: 14, name: "Petrol", label: "Petrol" }] }],
grouped = data.reduce(
(s => (r, a) => (a.facilities.forEach(b => !s.has(b.id) && s.add(b.id) && r.push(b)), r))(new Set),
[]
);
console.log(grouped);
.as-console-wrapper { max-height: 100% !important; top: 0; }

The solution using Array.prototype.reduce() and Set object:
var data = [{"id": 1,"facilities": [{"id": 10,"name": "Wifi","label": "Wifi"},{"id": 12,"name": "Toll","label": "Toll"}]},{"id": 2,"facilities": [{"id": 10,"name": "Wifi","label": "Wifi"},{"id": 12,"name": "Toll","label": "Toll"},{"id": 13,"name": "Snack","label": "Snack"}]},{"id": 3,"facilities": [{"id": 10,"name": "Wifi","label": "Wifi"},{"id": 12,"name": "Toll","label": "Toll"},{"id": 14,"name": "Petrol","label": "Petrol"}]}
];
var ids = new Set(),
result = data.reduce(function (r, o) {
o.facilities.forEach(function(v) { // iterating through nested `facilities`
if (!ids.has(v.id)) r.facilities.push(v);
ids.add(v.id); // saving only items with unique `id`
});
return r;
}, {facilities: []});
console.log(result);

const input = [
{
"id": 1,
"facilities": [
{
"id": 10,
"name": "Wifi",
"label": "Wifi"
},
{
"id": 12,
"name": "Toll",
"label": "Toll"
}
]
},
{
"id": 2,
"facilities": [
{
"id": 10,
"name": "Wifi",
"label": "Wifi"
},
{
"id": 12,
"name": "Toll",
"label": "Toll"
},
{
"id": 13,
"name": "Snack",
"label": "Snack"
}
]
},
{
"id": 3,
"facilities": [
{
"id": 10,
"name": "Wifi",
"label": "Wifi"
},
{
"id": 12,
"name": "Toll",
"label": "Toll"
},
{
"id": 14,
"name": "Petrol",
"label": "Petrol"
}
]
}
]
const result = []
const idx = []
for (const item of input) {
for (const facilityItem of item.facilities) {
if (!idx.includes(facilityItem.id)) {
idx.push(facilityItem.id)
result.push(facilityItem)
}
}
}
console.log(result)

A very simple and easily understood approach.
const data = [{
"id": 1,
"facilities": [{
"id": 10,
"name": "Wifi",
"label": "Wifi"
},
{
"id": 12,
"name": "Toll",
"label": "Toll"
}
]
},
{
"id": 2,
"facilities": [{
"id": 10,
"name": "Wifi",
"label": "Wifi"
},
{
"id": 12,
"name": "Toll",
"label": "Toll"
},
{
"id": 13,
"name": "Snack",
"label": "Snack"
}
]
},
{
"id": 2,
"facilities": [{
"id": 10,
"name": "Wifi",
"label": "Wifi"
},
{
"id": 12,
"name": "Toll",
"label": "Toll"
},
{
"id": 14,
"name": "Petrol",
"label": "Petrol"
}
]
}
];
let o = {};
let result = [];
data.forEach((d) => {
d.facilities.forEach((f) => {
o[f.id] = f;
});
});
for (let r in o) {
result.push(o[r]);
}
console.log(result);