Get Total From a Chosen Array in ES6

Question

I wanted to get the total productPrice from the chosenData array. I need to compare it from the mainData and only get its total value. My problem is that I'm getting undefined and how should I do it and is there a shorter way of doing it?

  const mainData = [
    {
        "id": "4324",
        "productName": "Apple",
        "productPrice": 250,
    },
    {
        "id": "656546b",
        "productName": "Banana",
        "productPrice": 500,
    },
    {
        "id": "5656",
        "productName": "Soup",
        "productPrice": 800,
    }
];

const chosenData = ['5656', '656546b']
  
  const newArray = chosenData.map((value, index) => ({
    productPrice: mainData.find((data) => data.id === value)
  }))


console.log(newArray.productPrice)

`newArray` is an Array. Arrays don’t have `productPrice` properties. Look at the `newArray` object itself (e.g. by logging it). You’re close. Returning an object with the `productPrice` property inside the `map` is not useful — the objects in `mainData` already have this property; no need to add yet another layer. The `find` is correct. All you need to do now is to sum by property, e.g. with `reduce`. See [Better way to sum a property value in an array](/q/23247859/4642212). — Sebastian Simon, Mar 30 '22 at 04:53

score 2 · Accepted Answer · answered Mar 30 '22 at 04:53

In your solution, newArray obtained through map is an array, and array does not have the attribute productPrice, therefore you got undefined.

You can filter out the object with matching id, then sum them up, ex:

mainData.filter(value=>chosenData.includes(value.id)).reduce((acc, cur)=>acc+cur.productPrice, 0)

score 2 · Answer 2 · answered Mar 30 '22 at 04:54

map returns a new array and it does not skip any element. You can use reduce and inside the reduce callback, use find. If an element with same id is found in the maindData it will return the object otherwise undefined. If it is not undefined , then get the value and accumulate it.

const mainData = [{
    "id": "4324",
    "productName": "Apple",
    "productPrice": 250,
  },
  {
    "id": "656546b",
    "productName": "Banana",
    "productPrice": 500,
  },
  {
    "id": "5656",
    "productName": "Soup",
    "productPrice": 800,
  }
];

const chosenData = ['5656', '656546b']

const newArray = chosenData.reduce((acc, curr) => {

  const findById = mainData.find(item => item.id === curr);
  findById && (acc += findById.productPrice)
  return acc;

}, 0)


console.log(newArray)

Tushar Shahi · Answer 3 · 2022-03-30T05:01:53.497

Your newArray is an array. You can't access its property like newArray.productPrice. You want to compute a value from your newArray, so you can use reduce(). Building up on your code

const mainData = [
    {
        "id": "4324",
        "productName": "Apple",
        "productPrice": 250,
    },
    {
        "id": "656546b",
        "productName": "Banana",
        "productPrice": 500,
    },
    {
        "id": "5656",
        "productName": "Soup",
        "productPrice": 800,
    }
];

const chosenData = ['5656', '656546b']
  
  const newSum = chosenData.map((value, index) => ({
    productPrice: mainData.find((data) => data.id === value)
  })).reduce((agg,x) => {
  return agg + x.productPrice.productPrice
  },0);


console.log(newSum)

If you don't want to complicate with too many properties you can use this code:

const mainData = [
    {
        "id": "4324",
        "productName": "Apple",
        "productPrice": 250,
    },
    {
        "id": "656546b",
        "productName": "Banana",
        "productPrice": 500,
    },
    {
        "id": "5656",
        "productName": "Soup",
        "productPrice": 800,
    }
];

const chosenData = ['5656', '656546b']
  
  const newSum = chosenData.map((value, index) => mainData.find((data) => data.id === value).productPrice).reduce((agg,x) => agg + x,0);


console.log(newSum)

score 0 · Answer 4 · answered Mar 30 '22 at 04:52

0

Because your newArray is an array of products filtered. Map returns an array. Probably try to reduce it to calculate the productPrice total or something. But the code is wrong at newArray.productPrice

answered Mar 30 '22 at 04:52

kaushik94

687
6
17

score 0 · Answer 5 · answered Mar 30 '22 at 04:58

You can reduce mainData and get totalPrice with O(n)

const mainData = [
    {
        "id": "4324",
        "productName": "Apple",
        "productPrice": 250,
    },
    {
        "id": "656546b",
        "productName": "Banana",
        "productPrice": 500,
    },
    {
        "id": "5656",
        "productName": "Soup",
        "productPrice": 800,
    }
];

const chosenData = ['5656', '656546b']
  
const totalPrice = chosenData.reduce((acc, {id, productPrice}) => {
    if (chosenData.includes(id)) {
        acc += productPrice;
    }
    return acc;
}, 0)


console.log(totalPrice)

score 0 · Answer 6 · answered Mar 30 '22 at 05:08

0

I think it should be

const newArray = chosenData.map(value => mainData.find(data => data.id === value).productPrice)

console.log(newArray.productPrice)

answered Mar 30 '22 at 05:08

max

1
1

Can you explain your code, and why your answer should fix the issue ? Please [edit] your answer :) – Elikill58 Mar 30 '22 at 09:24

Get Total From a Chosen Array in ES6

6 Answers6