Comparing one array to another and create a new array based on the differences

Question

Had my earlier question closed because I left out an important detail.

Say I have the following two Arrays

const salesDates = ['2021/06/30','2021/07/01','2021/07/02','2021/07/03','2021/07/04','2021/07/05','2021/07/06']

and

const jsonSalesData = [
         {date: '2021/07/01', company: 'ABC', sales: '32460'},
         {date: '2021/07/02', company: 'ABC', sales: '28165'},
         {date: '2021/07/03', company: 'ABC', sales: '31546'},
         {date: '2021/07/04', company: 'ABC', sales: '12654'},
         {date: '2021/07/05', company: 'ABC', sales: '26457'},
         {date: '2021/07/06', company: 'ABC', sales: '20351'},
         {date: '2021/07/07', company: 'ABC', sales: '56404'},
]

What I need to do is

Return the objects from jsonSalesData if the date in jsonSalesData matches the salesDates array
If there is a date in salesDates that is not in jsonSalesData add an object to the jsonSalesData with that date and set the sales to 0.

Desired Output

[
{date: '2021/06/30', company: 'ABC', sales: '0'},
{date: '2021/07/01', company: 'ABC', sales: '32460'},
{date: '2021/07/02', company: 'ABC', sales: '28165'},
{date: '2021/07/03', company: 'ABC', sales: '31546'},
{date: '2021/07/04', company: 'ABC', sales: '12654'},
{date: '2021/07/05', company: 'ABC', sales: '26457'},
{date: '2021/07/06', company: 'ABC', sales: '20351'},
]

notice the addition of the 1st object and the exclusion of the last object

I've tried to use forEach but it only accomplishes #1 (returns the dates in jsonSalesData which match to salesDates). It doesn't add the object if there is no match.

const n = [];
jsonSalesData.forEach(e => {
    if (salesDates.includes(e.date)){ 
      n.push(e);
  }
})
console.log(n);

I've also tried nested loops, but I can't seem to figure it out. Here's what I did for those:

    for (let i = 0; i < jsonSalesData.length; i++){
        for (let j = 0; j < salesData.length; j++){     
        if (jsonSalesData[i].date === salesData[j]){
console.log(jsonSalesData[i].company,jsonSalesData[i].date,jsonSalesData[i].sales)
        }
    
      }
    }

Same issues with map and filter -- I can't seem to look back at salesData and add an object back to jsonSalesData if something in salesData doesn't exist in jsonSalesData

Because there is a 2021/06/30 date in salesDates but not a 2021/06/30 in jsonSalesData. Therefore, it was added with a 0 sales. — Joey
– Joey, Commented Jul 15, 2021 at 21:50
salesDates.map(date => jsonSalesData.find(row=> row.date===date) || { date, sales: 0 }); — loop
– loop, Commented Jul 15, 2021 at 21:51
Show us what you have tried, or where you are stuck. SO is not a coding service. You can visit the help center, and take the tour to see what and How to Ask. — pilchard
– pilchard, Commented Jul 15, 2021 at 21:55

Claytronicon · Accepted Answer · 2021-07-15 23:25:08Z

2

if you don't care about adding the company name arbitrarily, you could do something like this

const salesDates = ['2021/06/30','2021/07/01','2021/07/02','2021/07/03','2021/07/04','2021/07/05','2021/07/06']
 
const jsonSalesData = [
         {date: '2021/07/01', company: 'ABC', sales: '32460'},
         {date: '2021/07/02', company: 'ABC', sales: '28165'},
         {date: '2021/07/03', company: 'ABC', sales: '31546'},
         {date: '2021/07/04', company: 'ABC', sales: '12654'},
         {date: '2021/07/05', company: 'ABC', sales: '26457'},
         {date: '2021/07/06', company: 'ABC', sales: '20351'},
         {date: '2021/07/07', company: 'ABC', sales: '56404'},
]

let updatedSalesData = salesDates.map(date => jsonSalesData.find(item=> item.date==date) || { date, company: 'ABC', sales: '0' }); 

console.log(updatedSalesData)

edited Jul 15, 2021 at 23:25

answered Jul 15, 2021 at 23:14

Claytronicon

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