working with nested object

Question

I think this is silly question and simple but I can't find any result in google and other resource

I have array of object like this

 const myArr = [
 [{
 id: 1,
 price: 200,
 }, {
 id: 2,
 price: 900,
 }, {
 id: 3,
 price: 100,
 }],
 [{
 id: 5,
 price: 100,
 }]
 ];

In other word I have an array and my array contain some array and each of inner array contain some object inside them

 arr [ [ {},{},{} ] , [ {} ] ]

now I want get two thing

1. count of all products ?
2. sum of all products ?

*(each object = one product)

• Sterling Archer: Could you show the code you have tried, please?

Answer 1

Flatten to a single array by spreading into Array.concat().

Use Array.reduce() to get the sum.

The count is flattened array's length.

const myArr = [[{"id":1,"price":200},{"id":2,"price":900},{"id":3,"price":100}],[{"id":5,"price":100}]];
const flattened = [].concat(...myArr);
const count = flattened.length;
const sum = flattened.reduce((s, o) => s + o.price, 0);
console.log('count', count);
console.log('sum', sum);

• Mihai Alexandru-Ionut: @OriDrori, we have same ideas but you was faster. Anyway, thumbs up and upvote.
• hamidreza nikoonia: @OriDrori my friend , now i have another question about this , you think every product have property { count : n } and this means the count of each products now how can i get sum price ??
• hamidreza nikoonia: @OriDrori , for example => [ [ { id:1 , price:100 , count:10 } ] , [ { id:2 , price:200 , count:5 } ] ]; i want this result (price of product)100 * (count of product)10 . .......
• Ori Drori: You actually have the answer. Look at the sum calculation in my code...
• hamidreza nikoonia: can u give me more details

Answer 2

You can use spread to flat the array:

var myArr = [
 [
 { 
 id:1,
 price:200,
 },
 { 
 id:2,
 price:900,
 },
 { 
 id:3,
 price:100,
 }
 ],
[
 { 
 id:5,
 price:100,
 }
]
];
var arr = [].concat(...myArr);
console.log('Length: ', arr.length);
var sum = arr.reduce((m, o) => m + o.price, 0);
console.log('Sum: ', sum);

Answer 3

You can use concat to wrap all objects within one single array.

Apply length property in order to find out the number of objects in the array and then reduce method to get the sum.

const myArr = [ [ { id:1, price:200, }, { id:2, price:900, }, { id:3, price:100, } ], [ { id:5, price:100, } ] ];
arr = myArr.reduce((acc, arr) => acc.concat(arr), []);
sum = arr.reduce((acc, item) => acc + item.price, 0);
console.log('count ' + arr.length);
console.log('sum ' + sum)

Answer 4

ES6

You can also use reduce method of array to get the required result

reduce can be used to iterate through the array, adding the current element value to the sum of the previous element values.

DEMO

const myArr = [[{id: 1,price: 200,}, {id: 2,price: 900,}, {id: 3,price: 100,}],[{id: 5,price: 100,}]];
 
let result = myArr.reduce((r,v)=>{
 r.count += v.length;
 r.sum += v.reduce((total,{price}) => total+price,0);
 return r;
},{count:0,sum:0}) 
console.log(result);

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