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Merge item in array of object with the same ID on Javascript

this is how the object look:
let data = [
{
brandId: '12345',
brand: 'Adidas',
item: {
name: 'Adidas 1',
price: '200',
},
},
{
brandId: '12345',
brand: 'Adidas',
item: {
name: 'Adidas 2',
price: '230',
},
},
{
brandId: '7878',
brand: 'Nike',
item: {
name: 'Nike 1',
price: '305',
},
}
];
i want the item object will merge if the object have the same brandID :
let data = [
{
brandId: '12345',
brand: 'Adidas',
item: [
{
name: 'Adidas 1',
price: '200',
},
{
name: 'Adidas 2',
price: '230',
},
],
},
{
brandId: '7878',
brand: 'Nike',
item: {
name: 'Nike 2',
price: '316',
},
},
];
is there any javascript syntax or method to do this ? and with an explanation will be very nice, Thank You

(Assuming that your output is just a typo and name/price doesn't actually changes) You can use array reduce
let data = [
{
brandId: '12345',
brand: 'Adidas',
item: {
name: 'Adidas 1',
price: '200',
},
},
{
brandId: '12345',
brand: 'Adidas',
item: {
name: 'Adidas 2',
price: '230',
},
},
{
brandId: '7878',
brand: 'Nike',
item: {
name: 'Nike 1',
price: '305',
},
}
];
const mergedItems = data.reduce((acc, curr) => {
// check if current exist on the accumulator
const exist = acc.find(brand => brand.brandId === curr.brandId);
// if it does, add the item on it
if (exist) {
return acc.map((brand) => {
if (brand.brandId === exist.brandId) {
return {
...brand,
item: brand.item.concat(curr.item),
}
}
})
}
// if it doesnt, add it on accumulator, and make the item array
return acc.concat({
...curr,
item: [
curr.item
]
})
})
(I wrote the code manually and not tested)

You can simply achieve this result using Map
let data = [
{
brandId: "12345",
brand: "Adidas",
item: {
name: "Adidas 1",
price: "200",
},
},
{
brandId: "12345",
brand: "Adidas",
item: {
name: "Adidas 2",
price: "230",
},
},
{
brandId: "7878",
brand: "Nike",
item: {
name: "Nike 1",
price: "305",
},
},
];
const dict = new Map();
data.forEach((o) => {
dict.get(o.brandId)
? dict.get(o.brandId).item.push(o.item)
: dict.set(o.brandId, { ...o, item: [o.item] });
});
const result = [];
for (let [k, v] of dict) {
v.item.length === 1 ? result.push({ ...v, item: v.item[0] }) : result.push(v);
}
console.log(result);
/* This is not a part of answer. It is just to give the output fill height. So IGNORE IT */
.as-console-wrapper { max-height: 100% !important; top: 0; }

How to find a value in an array of objects using JavaScript?

I want to:
Find the cheapest and most expensive food and drink.
Find the id and name of drinks and foods if their price is higher than 10.
My attempt:
let menu = [
{ id: 1, name: "Soda",price: 3.12,size: "4oz",type: "Drink" },
{ id: 2, name: "Beer", price: 6.50, size: "8oz", type: "Drink" },
{ id: 3, name: "Margarita", price: 12.99, size: "12oz", type: "Drink" },
{ id: 4, name: "Pizza", price: 25.10, size: "60oz", type: "Food" },
{ id: 5, name: "Kebab", price: 31.48, size: "42oz", type: "Food" },
{ id: 6, name: "Berger", price: 23.83, size: "99oz", type: "Food" }
]
I would be happy and thankful if anybody could help.Thanks in Advanced.

here is an example :
let menu = [
{ id: 1, name: "Soda",price: 3.12,size: "4oz",type: "Drink" },
{ id: 2, name: "Beer", price: 6.50, size: "8oz", type: "Drink" },
{ id: 3, name: "Margarita", price: 12.99, size: "12oz", type: "Drink" },
{ id: 4, name: "Pizza", price: 25.10, size: "60oz", type: "Food" },
{ id: 5, name: "Kebab", price: 31.48, size: "42oz", type: "Food" },
{ id: 6, name: "Berger", price: 23.83, size: "99oz", type: "Food" }
];
function getCheapest(array) {
return Math.min(...array.map(item => item.price));
}
function getExpensive(array) {
return Math.max(...array.map(item => item.price));
}
function getFoodsAndDrinksMoreThan(array, minVal = 10){
return array.filter(item => item.price > minVal).map(item => ({id: item.id, name: item.name}));
}
console.log(getCheapest(menu));
console.log(getExpensive(menu));
console.log(getFoodsAndDrinksMoreThan(menu));

The first one could be achieved with Array.prototype.reduce by comparing the first and second argument of the function you pass into it and returning the smaller one.
For 2. that sounds like a case for Array.prototype.filter to me.
Let me know if you need more guidance.

How to first combine properties of an object then remove the duplicates in an array of objects using Javascript

I have an array of objects here:
const arr = [
{ id: 1, name: "test1", quantity:1 },
{ id: 2, name: "test2", quantity:1 },
{ id: 2, name: "test3", quantity:1 },
{ id: 3, name: "test4", quantity:1 },
{ id: 4, name: "test5", quantity:1 },
{ id: 5, name: "test6", quantity:1 },
{ id: 5, name: "test7", quantity:1 },
{ id: 6, name: "test8", quantity:1 }
];
I want to add quantities of the duplicate objects together before removing them
So the result is:
const arr = [
{ id: 1, name: "test1", quantity:1 },
{ id: 2, name: "test3", quantity:2 },
{ id: 3, name: "test4", quantity:1 },
{ id: 4, name: "test5", quantity:1 },
{ id: 5, name: "test6", quantity:2 },
{ id: 6, name: "test8", quantity:1 }
];
I have seen variations of it done removing duplicates using map or reduce but I haven't seen anything that can what I want to accomplish in an eloquent way without using too many loops.
I have been thinking about how to best accomplish this all day and haven't found anything, any help would be appreciated

You can use reduce with an object to store the element with each id.
const arr = [
{ id: 1, name: "test1", quantity:1 },
{ id: 2, name: "test2", quantity:1 },
{ id: 2, name: "test3", quantity:1 },
{ id: 3, name: "test4", quantity:1 },
{ id: 4, name: "test5", quantity:1 },
{ id: 5, name: "test6", quantity:1 },
{ id: 5, name: "test7", quantity:1 },
{ id: 6, name: "test8", quantity:1 }
];
const res = Object.values(
arr.reduce((acc,curr)=>{
acc[curr.id] = acc[curr.id] || {...curr, quantity: 0};
acc[curr.id].quantity += curr.quantity;
return acc;
}, {})
);
console.log(res);

const arr = [
{ id: 1, name: "test1", quantity: 1 },
{ id: 2, name: "test2", quantity: 1 },
{ id: 2, name: "test3", quantity: 1 },
{ id: 3, name: "test4", quantity: 1 },
{ id: 4, name: "test5", quantity: 1 },
{ id: 5, name: "test6", quantity: 1 },
{ id: 5, name: "test7", quantity: 1 },
{ id: 6, name: "test8", quantity: 1 }
];
var result = arr.reduce(function (r, a) {
r[a.id] = r[a.id] || { id: a.id, quantity: 0, name: a.name };
r[a.id].quantity += a.quantity;
return r;
}, Object.create(null));
console.log(JSON.stringify(result));

Using forEach loop and build object with aggregated quantity count.
const convert = (arr) => {
const res = {};
arr.forEach(({ id, ...rest }) =>
res[id] ? (res[id].quantity += 1) : (res[id] = { id, ...rest })
);
return Object.values(res);
};
const arr = [
{ id: 1, name: "test1", quantity: 1 },
{ id: 2, name: "test2", quantity: 1 },
{ id: 2, name: "test3", quantity: 1 },
{ id: 3, name: "test4", quantity: 1 },
{ id: 4, name: "test5", quantity: 1 },
{ id: 5, name: "test6", quantity: 1 },
{ id: 5, name: "test7", quantity: 1 },
{ id: 6, name: "test8", quantity: 1 },
];
console.log(convert(arr));

Join two objects just like SQL inner join

I have two objects like:
countries = [
{ id: 1, name: 'India', image: 'thumb15.jpg' },
{ id: 2, name: 'Africa', image: 'thumb11.jpg' },
{ id: 3, name: 'Kenya', image: 'thumb10.jpg' }
];
cities = [
{ id: 1, name: 'Ahmedabad', country_id: 1 },
{ id: 2, name: 'Vadodara', country_id: 1 },
{ id: 3, name: 'Cairo', country_id: 2 },
{ id: 4, name: 'Kinshasa', country_id: 2 },
{ id: 5, name: 'Luanda', country_id: 2 },
{ id: 6, name: 'Nairobi', country_id: 3 },
{ id: 7, name: 'Nakuru', country_id: 3 },
{ id: 8, name: 'Mombasa', country_id: 3 },
];
I want to combine these two Objects, just like SQL have INNER JOIN
for example, I want to perform below operation (query) on the above two objects,
SELECT * from countries INNER JOIN cities ON cities.country_id = countries.id
and my expected output will look like:
expected_result = [
{ id: 1, name: "Ahmedabad", country_id: 1, country_name: "India", country_image: "thumb15.jpg" },
{ id: 2, name: "Vadodara", country_id: 1, country_name: "India", country_image: "thumb15.jpg" },
{ id: 3, name: "Cairo", country_id: 2, country_name: "Africa", country_image: "thumb11.jpg" },
{ id: 4, name: "Kinshasa", country_id: 2, country_name: "Africa", country_image: "thumb11.jpg" },
{ id: 5, name: "Luanda", country_id: 2, country_name: "Africa", country_image: "thumb11.jpg" },
{ id: 6, name: "Nairobi", country_id: 3, country_name: "Kenya", country_image: "thumb10.jpg" },
{ id: 7, name: "Nakuru", country_id: 3, country_name: "Kenya", country_image: "thumb10.jpg" },
{ id: 8, name: "Mombasa", country_id: 3, country_name: "Kenya", country_image: "thumb10.jpg" }
];
Thanks in advance.

It is possible to use map function and Map collection to get desired country:
const uniqueCountries = new Map(countries.map(s => [s.id, s]));
const result = cities.map(s => ({ ...s,
country_name: uniqueCountries.get(s.country_id).name }));
An example:
let countries = [
{ id: 1, name: 'India', image: 'thumb15.jpg' },
{ id: 2, name: 'Africa', image: 'thumb11.jpg' },
{ id: 3, name: 'Kenya', image: 'thumb10.jpg' }
];
let cities = [
{ id: 1, name: 'Ahmedabad', country_id: 1 },
{ id: 2, name: 'Vadodara', country_id: 1 },
{ id: 3, name: 'Cairo', country_id: 2 },
{ id: 4, name: 'Kinshasa', country_id: 2 },
{ id: 5, name: 'Luanda', country_id: 2 },
{ id: 6, name: 'Nairobi', country_id: 3 },
{ id: 7, name: 'Nakuru', country_id: 3 },
{ id: 8, name: 'Mombasa', country_id: 3 },
];
const uniqueCountries = new Map(countries.map(s => [s.id, s]));
const result = cities.map(s => ({ ...s,
country_name: uniqueCountries.get(s.country_id).name }));
console.log(result);
UPDATE:
map method creates new array from the calling array. In addition, you can add new properties to your object you want:
let countries = [
{ id: 1, name: 'India', image: 'thumb15.jpg' },
{ id: 2, name: 'Africa', image: 'thumb11.jpg' },
{ id: 3, name: 'Kenya', image: 'thumb10.jpg' }
];
const countriesWithShortCountryNames = countries.map(s=> ({...s,
shortName: s.name.substring(0, 3)}))
console.log(countriesWithShortCountryNames)
Map collection:
The Map object holds key-value pairs and remembers the original
insertion order of the keys.

You could take a hash table for all items of countries, where id is the key and the value is a new object in the wanted format.
{
1: {
country_name: "India",
image: "thumb15.jpg"
},
2: {
country_name: "Africa",
image: "thumb11.jpg"
},
3: {
country_name: "Kenya",
image: "thumb10.jpg"
}
}
Then map a new objects with the original key/value and new properties from the hash table.
Methods used, in order of appearance:
Array#reduce
destructuring assignment with assigning to new variable name
Array#map
var countries = [{ id: 1, name: 'India', image: 'thumb15.jpg' }, { id: 2, name: 'Africa', image: 'thumb11.jpg' }, { id: 3, name: 'Kenya', image: 'thumb10.jpg' }],
cities = [{ id: 1, name: 'Ahmedabad', country_id: 1 }, { id: 2, name: 'Vadodara', country_id: 1 }, { id: 3, name: 'Cairo', country_id: 2 }, { id: 4, name: 'Kinshasa', country_id: 2 }, { id: 5, name: 'Luanda', country_id: 2 }, { id: 6, name: 'Nairobi', country_id: 3 }, { id: 7, name: 'Nakuru', country_id: 3 }, { id: 8, name: 'Mombasa', country_id: 3 }],
countriesH = countries.reduce((r, { id, name: country_name, ...o }) =>
(r[id] = { country_name, ...o }, r), {}),
result = cities.map(o => ({ ...o, ...countriesH[o.country_id] }));
console.log(result);
.as-console-wrapper { max-height: 100% !important; top: 0; }

I wrote a library (which emulates dotnet's linq) which makes this a breeze:
import { blinq } from "blinq";
//...
const joinedData = blinq(countries)
.join(
cities,
co => co.id,
ci => ci.country_id,
(country, city) => ({ country, city })
)
.toArray();
const {
blinq
} = window.blinq;
const countries = [{
id: 1,
name: "India",
image: "thumb15.jpg"
},
{
id: 2,
name: "Africa",
image: "thumb11.jpg"
},
{
id: 3,
name: "Kenya",
image: "thumb10.jpg"
}
];
const cities = [{
id: 1,
name: "Ahmedabad",
country_id: 1
},
{
id: 2,
name: "Vadodara",
country_id: 1
},
{
id: 3,
name: "Cairo",
country_id: 2
},
{
id: 4,
name: "Kinshasa",
country_id: 2
},
{
id: 5,
name: "Luanda",
country_id: 2
},
{
id: 6,
name: "Nairobi",
country_id: 3
},
{
id: 7,
name: "Nakuru",
country_id: 3
},
{
id: 8,
name: "Mombasa",
country_id: 3
}
];
const joinedData = blinq(countries)
.join(
cities,
co => co.id,
ci => ci.country_id,
(country, city) => ({
country,
city
})
)
.toArray();
console.log(JSON.stringify(joinedData, null, 2))
<script src="https://cdn.jsdelivr.net/npm/blinq"></script>

Count duplicates and order them in array of objects Javascript

I have the following array of objects:
[
{
id: 1,
someOtherStuff: 'abc,
Drink: { name: 'Coca-Cola', price: 2.5 }
},
{
id: 2,
someOtherStuff: 'def,
Drink: { name: 'Fanta Orange', price: 3 }
},
{
id: 3,
someOtherStuff: 'ghi,
Drink: { name: 'Sprite', price: 1.8 }
},
{
id: 6,
someOtherStuff: 'jkl,
Drink: { name: 'Coca-Cola', price: 2.5 }
},
{
id: 7,
someOtherStuff: 'mno,
Drink: { name: 'Coca-Cola', price: 2.5 }
}
]
i want to group them by duplicates like this:
[
{
count: 3,
drinkName: 'Coca-Cola',
price: 2.5
},
{
count: 1,
drinkName: 'Fanta Orange',
price: 3
},
{
count: 1,
drinkName: 'Sprite',
price: 1.8
}
]
I have tried in several ways to map a new array.But unfortunately I can't get it to work
I hope someone can help me with that

let result= {};
inputArray.map((item)=>{
let key = `${item.Drink.name}-${item.Drink.price}`;
if(result[key]){
result[key].count = result[key].count +1;
}else{
result[key] = {count:1,drinkName:item.Drink.name,price:item.Drink.price};
}
});
result = Object.values(result);