How to calculate and create new object value from two different arrays in Javascript

Question

var array1 = [{issueCount: 16, failCount: 38, id: 1},
{issueCount: 15, failCount: 37, id: 2},
{issueCount: 15, failCount: 34, id: 3}];

var array2 = [{id: 1, totalAttempts: 57},
{id: 2, totalAttempts: 59},
{id: 3, totalAttempts: 67},
{id: 4, totalAttempts: 59}];

I have two arrays. From the above arrays, I need to calculate failure Percentage using the (array1. fail count/array2.totalAttempts) * 100 [id is common between two arrays]. And the final array wants in the below format.

outputArray = [{id: 1, issueCount: 16, failCount: 38, percentage: 66.66},
{id: 2, issueCount: 15, failCount: 37, percentage: 62.71},
{id: 3, issueCount: 15, failCount: 34, percentage: 50.74}];

Thanks in advance.

outputArray = []; array1.forEach(function(dataItem1, idx) { var array2Items = array2[idx]; var outputItems = {}; if(dataItem1.id == array2Items.id){ outputItems.id = dataItem1.id; outputItems.issueCount = dataItem1.issueCount; outputItems.failCount = dataItem1.failCount; outputItems.percentage = (dataItem1.failCount/array2Items.totalAttempts)*100; outputArray.push(outputItems); } }); — Vadivel A
– Vadivel A, Commented Aug 3, 2021 at 10:13
The above code is working fine, when I have array1 length and array2 length are same and array2 length > array1 length. But, when I have array1 length > array 2 length it is not working. what is code improvement should I need to add to achieve for all the scenario. Thanks in advance. — Vadivel A
– Vadivel A, Commented Aug 9, 2021 at 14:11
You should really take the tour to learn how this site works. Both solutions provided will solve your problem even with diffrent array lengths. If you just write a comment to your own answer no one will see it — kevinSpaceyIsKeyserSöze
– kevinSpaceyIsKeyserSöze, Commented Aug 10, 2021 at 9:06

kevinSpaceyIsKeyserSöze · Accepted Answer · 2021-08-03 10:08:17Z

1

You can achieve this with a simple for loop.

Just check if the id exists in the second array, if so make your calculations.

const array1 = [{issueCount: 16, failCount: 38, id: 1},
{issueCount: 15, failCount: 37, id: 2},
{issueCount: 15, failCount: 34, id: 3}];

const array2 = [{id: 1, totalAttempts: 57},
{id: 2, totalAttempts: 59},
{id: 3, totalAttempts: 67},
{id: 4, totalAttempts: 59}];

const outputArray = [];

array1.forEach(i1 => {
  const i2 = array2.find(i => i.id === i1.id);
  if(i2) {
    outputArray.push({
      id: i1.id, 
      issueCount: i1.issueCount, 
      failCount: i1.failCount,
      percentage: (i1.failCount / i2.totalAttempts) * 100
      }); 
  }
});
console.log(outputArray)

answered Aug 3, 2021 at 10:08

kevinSpaceyIsKeyserSöze

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Comments

Yosvel Quintero · Accepted Answer · 2021-08-03 10:42:38Z

1

You can do:

const array1 = [{issueCount: 16, failCount: 38, id: 1},{issueCount: 15, failCount: 37, id: 2},{issueCount: 15, failCount: 34, id: 3}]
const array2 = [{id: 1, totalAttempts: 57},{id: 2, totalAttempts: 59},{id: 3, totalAttempts: 67},{id: 4, totalAttempts: 59}]

const mergedArrays = Object.values([...array1, ...array2].reduce((a, c) => (a[c.id] = { ...a[c.id], ...c }, a), {}))
const outputArray = mergedArrays
  .filter(o => o.issueCount && o.totalAttempts)
  .map(({ id, issueCount, failCount, percentage, totalAttempts }) => ({
    id, 
    issueCount, 
    failCount,
    percentage: Math.round(failCount / totalAttempts * 100 * 100) / 100
  }))
  
console.log(outputArray)

edited Aug 3, 2021 at 10:42

answered Aug 3, 2021 at 10:17

Yosvel Quintero

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Comments

Vadivel A · Accepted Answer · 2021-08-10 03:59:19Z

0

Thank you all for your posts. I have also find the solution below.

outputArray = []; 
    array1.forEach(function(dataItem1, idx) { 
        var array2Items = array2[idx]; 
        var outputItems = {}; 
        if (dataItem1 && array2Items){
        if(dataItem1.id == array2Items.id){ 
            outputItems.id = dataItem1.id; 
            outputItems.issueCount = dataItem1.issueCount; 
            outputItems.failCount = dataItem1.failCount; 
            outputItems.percentage = ((dataItem1.failCount/array2Items.totalAttempts)*100).toFixed(2); 
            outputArray.push(outputItems); 
        } 
        }
    });
    
    console.log(outputArray);

answered Aug 10, 2021 at 3:59

Vadivel A

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2 Comments

kevinSpaceyIsKeyserSöze Over a year ago

This apporach will work with your test data but is error prone.

Vadivel A Over a year ago

Hi Kevin, I agree. The real-time scenario is different than this post. In the original code, I am using find() and other company-specific proprietary tools. So, it makes us not error-prone. Thank you

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