Javascript - reduce method returning object object

Question

I have an array topArr that I am attempting to get the sum of the results object. I using the .reduce() method in order to accomplish this. I am then declaring another variable to equal the sum with comma placements.

I have two attempt code snippet examples below.

First, I am getting a return value of [object Object]48,883.

Second example, I am getting a return value of the first number in the array, it is not combining the other object.

I am expecting the result of both results combined to equal the amount 543,810

Here are my code snippets.

let topArr = [
        { result: "494,927", risk: "HIGH", sector: "Online" },
        { result: "48,883", risk: "HIGH", sector: "Retail Stores" },
    ],
    
 sum = topArr.reduce(function (a, e) {
        return a + Number(e.result.replace(/(,\s*)+/g, '').trim());
    })

    let sumComma = sum.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ",");
    
    console.log(sumComma)

let topArr = [
        { result: "494,927", risk: "HIGH", sector: "Online" },
        { result: "48,883", risk: "HIGH", sector: "Retail Stores" },
    ],
    
 sum = topArr.reduce(function (e) {
        return Number(e.result.replace(/(,\s*)+/g, '').trim());
    })

    let sumComma = sum.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ",");
    
    console.log(sumComma)

CertainPerformance · Accepted Answer · 2020-05-27 17:03:43Z

5

You aren't passing an initial value to the .reduce, so the initial value defaults to the first item in the array, which is an object - so a + Number(...) results in concatenating the object (coerced to a string) with the Number call.

Pass an initial value of 0 instead:

let topArr = [{
      result: "494,927",
      risk: "HIGH",
      sector: "Online"
    },
    {
      result: "48,883",
      risk: "HIGH",
      sector: "Retail Stores"
    },
  ],

  sum = topArr.reduce(function(a, e) {
    return a + Number(e.result.replace(/(,\s*)+/g, '').trim());
  }, 0)

let sumComma = sum.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ",");

console.log(sumComma)

answered May 27, 2020 at 17:03

CertainPerformance

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javascwipt · Accepted Answer · 2020-05-27 17:07:07Z

0

You need to give reduce an initial value to add up from

const sum = topArr.reduce((acc, cur) => {
     return acc + Number(cur.result.replace(/(,\s*)+/g, '').trim());
}, 0)

answered May 27, 2020 at 17:07

javascwipt

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