How to calculate objects from an array - javascript

Question

Hello I have these objects in an array and I want to get the total of thier prices after multiply each price with it's quantity.

[
 {
  productId:55,
  productName:"Libero",
  productImage:"https://www.albadrbakelser.se/en/wp-content/uploads/sites/2/2019/08/albadr-logo-background.jpg",
  productQuantity:7,
  productPrice:100
 },
 {
  productId:56,
  productName:"Nam Libero Tempore",
  productImage:"https://www.albadrbakelser.se/en/wp-content/uploads/sites/2/woocommerce-placeholder.png",
  productQuantity:8,
  productPrice:150
 }
]

I want to multiply first productQuantity * productPrice then get the sum of productPrice from all products after multiplication to get the total

That's what I tried so long

const raw = [{a: 1}, {a: 2}, {a: 3}, {b: 4}, {b: 5}];

const calcSums = someArray => someArray
  .reduce( (sums, val) => {
    Object.keys(val)
      .forEach( v => 
          sums[`sum-${v}`] = !sums[`sum-${v}`] ? val[v] : sums[`sum-${v}`] + val[v] );
    return sums;
  }, {} );


console.log(calcSums(raw));

// the method is generic, so this works too (as long as the values are numbers)
const raw2 = [{a: 1, b:3, c:7}, {a: 2}, {a: 3}, {b: 4}, {b: 5}, {c: 9}];
console.log(calcSums(raw2));

Tyler Smith · Accepted Answer · 2020-06-21 22:07:55Z

2

If I understand correctly, you're trying to get a single number at the end with the total value of all your inventory. Try this:

let productArray = [
 {
  productId:55,
  productName:"Libero",
  productImage:"https://www.albadrbakelser.se/en/wp-content/uploads/sites/2/2019/08/albadr-logo-background.jpg",
  productQuantity:7,
  productPrice:100
 },
 {
  productId:56,
  productName:"Nam Libero Tempore",
  productImage:"https://www.albadrbakelser.se/en/wp-content/uploads/sites/2/woocommerce-placeholder.png",
  productQuantity:8,
  productPrice:150
 }
]

productArray.reduce((accumulator, { productPrice, productQuantity }) => {
  return accumulator + (productQuantity * productPrice)
}, 0)

// returns 1900

answered Jun 21, 2020 at 22:07

Tyler Smith

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1 Comment

Maher Aldous Over a year ago

Thank you but I really didn't know how to get productQuantity and productPrice in the same time when I loop through them

djcaesar9114 · Accepted Answer · 2020-06-21 22:03:40Z

2

You can use map and reduce:

map applies a function to all the elements of the array, in this case the multiplication
reduce (with the function I use) sums all the elements of the array.

let prods = [
 {
  productId:55,
  productName:"Libero",
  productImage:"https://www.albadrbakelser.se/en/wp-content/uploads/sites/2/2019/08/albadr-logo-background.jpg",
  productQuantity:7,
  productPrice:100
 },
 {
  productId:56,
  productName:"Nam Libero Tempore",
  productImage:"https://www.albadrbakelser.se/en/wp-content/uploads/sites/2/woocommerce-placeholder.png",
  productQuantity:8,
  productPrice:150
 }
]

var total = prods.map(x=>x.productQuantity*x.productPrice).reduce((a,b)=>a+b)

console.log(total)

answered Jun 21, 2020 at 22:03

djcaesar9114

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Comments

mickl · Accepted Answer · 2020-06-21 22:05:01Z

1

You can use array.reduce to aggregate the data from an array of objects:

let input = [
 {
  productId:55,
  productName:"Libero",
  productImage:"https://www.albadrbakelser.se/en/wp-content/uploads/sites/2/2019/08/albadr-logo-background.jpg",
  productQuantity:7,
  productPrice:100
 },
 {
  productId:56,
  productName:"Nam Libero Tempore",
  productImage:"https://www.albadrbakelser.se/en/wp-content/uploads/sites/2/woocommerce-placeholder.png",
  productQuantity:8,
  productPrice:150
 } 
]

let result = input.reduce((acc,cur) => acc + cur.productQuantity * cur.productPrice, 0);

console.log(result);

answered Jun 21, 2020 at 22:05

mickl

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Comments

Ahmed Hammad · Accepted Answer · 2020-06-21 22:05:29Z

1

let totalPrice = someArr.reduce((total, item) => {
  total + (item.productQuantity * item.productPrice)
}, 0);

answered Jun 21, 2020 at 22:05

Ahmed Hammad

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1 Comment

ysf Over a year ago

While this code may resolve the OP's issue, it is best to include an explanation as to how your code addresses the OP's issue. In this way, future visitors can learn from your post, and apply it to their own code. SO is not a coding service, but a resource for knowledge. Also, high quality, complete answers are more likely to be upvoted. These features, along with the requirement that all posts are self-contained, are some of the strengths of SO as a platform, that differentiates it from forums. You can edit to add additional info &/or to supplement your explanations with source documentation.

sonEtLumiere · Accepted Answer · 2020-06-21 22:12:40Z

0

I hope this helps

var total = 0;
for(let obj of arr){
  obj.mult = obj.productQuantity * obj.productPrice;
}
for(let obj of arr){
  total += obj.mult;
}
console.log(total);

answered Jun 21, 2020 at 22:12

sonEtLumiere

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