We Keep Coding

How to Filter Nested Object Array Without affecting References in JavaScript

Just want to remove all the items other than 14 from the parentId: 1001 and add that item to another object.
I want to filter the array without affecting the source array.
var Data = [{
"id": 1001,
"text": "A",
"items": [
{ "id": 13, "text": "Thirteen" },
{ "id": 14, "text": "Fourteen" },
{ "id": 15, "text": "Fifteen", }
]
},
{
"id": 1002,
"text": "B",
"items": [
{ "id": 21, "text": "TwentyOne" },
{ "id": 22, "text": "TwentyTwo" },
{ "id": 23, "text": "TwentyThree", }
]
}
]
var childId = 14;
Data.items.filter((x) => {
return x.id != childId;
})
//this is affecting the source array (Data)
//after searching on internet found a solution
Data.items.filter((x) => {
return x.id childId;
}).map(function(x) {
return x
});

Your Data has no items property: it is an array, so you actually have Data[0].items, Data[1].items, ...
NB: it is common practice to use camelCase for such variable names, and reserve PascalCase for constructors/classes
Here is how you could do it:
const data = [{"id": 1001,"text": "A","items": [{ "id": 13, "text": "Thirteen" }, { "id": 14, "text": "Fourteen" }, { "id": 15, "text": "Fifteen", }]},{"id": 1002,"text": "B","items": [{ "id": 21, "text": "TwentyOne" }, { "id": 22, "text": "TwentyTwo" }, { "id": 23, "text": "TwentyThree", }]}]
const childId = 14;
const newData = data.map(obj => ({
...obj,
items: obj.items.filter(x => x.id != childId)
}));
console.log(newData);

As you want to filter out a few items from an array object and want to add those into another object.
You can also achieve this requirement by doing a deep copy of an original array with the help of structuredClone() API and then iterating it using Array#forEach method.
Live demo :
const data=[
{
"id":1001,
"text":"A",
"items":[
{
"id":13,
"text":"Thirteen"
},
{
"id":14,
"text":"Fourteen"
},
{
"id":15,
"text":"Fifteen",
}
]
},
{
"id":1002,
"text":"B",
"items":[
{
"id":21,
"text":"TwentyOne"
},
{
"id":22,
"text":"TwentyTwo"
},
{
"id":23,
"text":"TwentyThree",
}
]
}
];
const clone = structuredClone(data);
let remainingItems = [];
clone.forEach(obj => {
if (obj.id === 1001) {
remainingItems = obj.items.filter(({ id }) => id !== 14);
obj.items = obj.items.filter(({ id }) => id === 14);
} else {
obj.items = [...obj.items, ...remainingItems];
}
})
console.log('cloned data_____', clone);
console.log('source data_____', data);

If the 'id' key is duplicated among the objects in the array, how to delete the object [duplicate]

This question already has answers here:
How to remove all duplicates from an array of objects?
(77 answers)
Closed 4 months ago.
If the 'id' key is duplicated among the objects in the array, how to delete the object
I tried using filter, map, and set, but it doesn't work.
It's not a one-dimensional array, so I don't know how to do it.
as-is
"category": {
"key": 1,
"order": 1,
"list": [
{
"id": "12345",
...
},
{
"id": "12345",
...
},
{
"id": "67890",
...
},
]
}
to-be
"category": {
"key": 1,
"order": 1,
"list": [
{
"id": "12345",
...
},
{
"id": "67890",
...
},
]
}

We iterate over that list using reduce function, then we checked whether the key we are accessing is visited or not with keys parameter of reduce method, and if it's not visited then we just push that object to a filtered array and returning keys array to keep it updated.
const data = {
"category": {
"key": 1,
"order": 1,
"list": [{
"id": "12345"
},
{
"id": "12345"
},
{
"id": "67890"
},
]
}
}
let filtered = [];
data.category.list.reduce((keys, currentObject) => {
if (!keys.includes(currentObject.id)) { //checking if current oject id is present in keys or not
// if not present than we will just push that object in
keys.push(currentObject.id);
//getting filttered object
filtered.push(currentObject);
}
return keys; //returning keys to update it
}, [])
data.category.list = filtered; //updating list
console.log(data);

A solution based on #Nick's comment
let data ={
"category": {
"key": 1,
"order": 1,
"list": [
{
"id": "12345"
},
{
"id": "12345"
},
{
"id": "67890"
},
]
}
}
let uniq = data.category.list.filter((o,i,a) => a.findIndex(o2 => o2.id == o.id) == i)
data.category.list = uniq
console.log(data)

You can use a set to track if id
const category = [{
"category": {
"key": 1,
"order": 1,
"list": [{
"id": "12345",
},
{
"id": "12345",
},
{
"id": "67890",
},
]
}
}]
const z = category.map(elem => {
const set = new Set()
return {
...elem,
category: {
...elem.category,
list: elem.category.list.reduce((acc, curr) => {
if (!set.has(curr.id)) {
set.add(curr.id);
acc.push(curr)
}
return acc;
}, [])
}
}
});
console.log(z)

Javascript - grab value inside of an object nested within an object

I am trying to grab a value of a key inside of an object in an array which itself is an object in an array.
Here is what it looks like:
var books = [
{
"title": "title1",
"author": "author1",
"users": [
{
"id": 1,
"name": "Isidro"
},
{
"id": 4,
"name": "Jose Miguel"
},
{
"id": 3,
"name": "Trinidad"
}
]
},
{
"title": "title2",
"author": "author2",
"users": [
{
"id": 4,
"name": "Jose Miguel"
},
{
"id": 5,
"name": "Beatriz"
},
{
"id": 6,
"name": "Rosario"
}
]
},
What I am trying to do, 2 things:
First:
when I click on a user name in the HTML, I want to match the name clicked with the same user name in all the objects it is present in.
Second:
display the title of the books this user name is present in.
For example: when I click on Jose Miguel I want to see the 2 books he has read.
At the moment I have this:
var btnUser = document.querySelectorAll(".individualUsers");
for (var i = 0; i < btnUser.length; i++) {
btnUser[i].addEventListener("click", function() {
var clickedUser = this.innerText
var userBooks = books
.filter(x => x.users.name.indexOf(clickedUser) > -1)
.map(x => ` <li>${x.title}</li> <li>${x.author}</li>`);
console.log(clickedUser);
});
}
My problem is x.users.name.indexOf(clickedUser)is not accessing the user name.

You need to search inside the users array as well, one neat way is to do so with Array.some that return true if some of the conditional is true.
const books = [{
"title": "title1",
"author": "author1",
"users": [{
"id": 1,
"name": "Isidro"
},
{
"id": 4,
"name": "Jose Miguel"
},
{
"id": 3,
"name": "Trinidad"
}
]
},
{
"title": "title2",
"author": "author2",
"users": [{
"id": 4,
"name": "Jose Miguel"
},
{
"id": 5,
"name": "Beatriz"
},
{
"id": 6,
"name": "Rosario"
}
]
}
];
const clickedUser = 'Jose Miguel';
var userBooks = books
.filter(x => x.users.some(user => user.name.indexOf(clickedUser) > -1));
console.log(userBooks);

Filter multiple objects from array

I'm trying to filter an array of objects where the filter is another array (of integers) which are values of properties of the first array. I've managed to make it work but I'm not sure if it's the best way. Since I'm a beginner in javascript, I'd appreciate any suggestions/improvements.
The items.json file contains an object with an array of objects. I want to filter all the objects (within that array) that have an id equal to the "ids" on the itemsids array.
code:
const itemsall = require('./items.json');
let itemsids = [1, 403, 3];
let filtereditems = [];
itemsids.forEach(id => {
itemsall.items.forEach(item => {
if (id === item.id) {
filtereditems.push(item);
}
});
});
items.json (a small part of it)
{
"items": [
{
"id": 0,
"name": "Egg",
"img": "http://www.serebii.net/pokemongo/items/egg.png"
},
{
"id": 1,
"name": "Pokeball",
"img": "http://www.serebii.net/pokemongo/items/20pokeballs.png"
},
{
"id": 2,
"name": "Greatball",
"img": "http://www.serebii.net/pokemongo/items/greatball.png"
}
]
}
output: (expected)
[
{
"id": 0,
"name": "Egg",
"img": "http://www.serebii.net/pokemongo/items/egg.png"
},
{
"id": 403,
"name": "Cool Incense",
"img": "http://www.serebii.net/pokemongo/items/incense.png"
},
{
"id": 3,
"name": "Ultraball",
"img": "http://www.serebii.net/pokemongo/items/ultraball.png"
}
]
Thanks!

You can use filter() and indexOf() to return filtered array.
var data = {
"items": [{
"id": 0,
"name": "Egg",
"img": "http://www.serebii.net/pokemongo/items/egg.png"
}, {
"id": 1,
"name": "Pokeball",
"img": "http://www.serebii.net/pokemongo/items/20pokeballs.png"
}, {
"id": 2,
"name": "Greatball",
"img": "http://www.serebii.net/pokemongo/items/greatball.png"
}]
}
let itemsids = [1, 403, 3];
var result = data.items.filter(function(e) {
return itemsids.indexOf(e.id) != -1
})
console.log(result)
With ES6/ES7 you can use includes() like this.
var result = data.items.filter((e) => itemsids.includes(e.id));

Lodash keyBy for multiple nested level arrays

I have an array of object, and i want to convert it into a map of key value pairs with the id as the key. However, I want to do it for both the root level and within the recipes attribute.
Array resp:
[
{
"id": "1",
"recipes": [
{
"id": 4036
},
{
"id": 4041
}
]
},
{
"id": "2",
"recipes": [
{
"id": 4052
},
{
"id": 4053
}
]
}
]
I came across _.keyBy() which maps an attribute as the key, but it doesn't allow nested levels.
Function:
var respObj = _.keyBy(resp, 'id');
Is there an elegant solution to massage resp to make all the objects nested within the array use id as key?
thanks!

you can do it with _.keyBy and _.mapValues
_.chain(resp)
.keyBy('id')
.mapValues(function(item) {
item.recipes = _.keyBy(item.recipes, 'id');
return item;
})
.value();

This is a generic solution that runs _.keyBy recursively on arrays, and the objects inside them:
function deepKeyBy(arr, key) {
return _(arr)
.map(function(o) { // map each object in the array
return _.mapValues(o, function(v) { // map the properties of the object
return _.isArray(v) ? deepKeyBy(v, key) : v; // if the property value is an array, run deepKeyBy() on it
});
})
.keyBy(key); // index the object by the key
}
I've added another level of data in the example (ingredients):
function deepKeyBy(arr, key) {
return _(arr)
.map(function(o) {
return _.mapValues(o, function(v) {
return _.isArray(v) ? deepKeyBy(v, key) : v;
});
})
.keyBy(key);
}
var arr = [{
"id": "1",
"recipes": [{
"id": 4036,
"ingerdients": [{
"id": 5555555
}, {
"id": 5555556
}, {
"id": 5555557
}]
}, {
"id": 4041
}]
}, {
"id": "2",
"recipes": [{
"id": 4052
}, {
"id": 4053
}]
}];
var result = deepKeyBy(arr, 'id');
console.log(result);
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.2/lodash.min.js"></script>

You could get a flattened collection of recipes, concatenate the response and then key by id:
var result = _.chain(resp)
.flatMap('recipes')
.concat(resp)
.keyBy('id')
.value()
The flatMap call will pluck all the recipes from the response and flatten the arrays so we're left with this:
[
{ "id": 4036 },
{ "id": 4041 },
{ "id": 4052 },
{ "id": 4053 }
]
The response is then appended to this array using concat so we then have:
[
{ "id": 4036 },
{ "id": 4041 },
{ "id": 4052 },
{ "id": 4053 },
{ "id": "1", recipes: ... },
{ "id": "2", recipes: ... }
]
Finally we use keyBy to get the required structure .
var resp = [
{
"id": "1",
"recipes": [
{
"id": 4036
},
{
"id": 4041
}
]
},
{
"id": "2",
"recipes": [
{
"id": 4052
},
{
"id": 4053
}
]
}
]
var result = _.chain(resp)
.flatMap('recipes')
.concat(resp)
.keyBy('id')
.value()
document.getElementById('result').textContent = JSON.stringify(result);
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.15.0/lodash.min.js"></script>
<p>
<pre id="result"></pre>
</p>