Create object from JSON response remove unwanted key-values

Question

I am getting JSON response as below:

bills : [
             {
                id: '111',
                date: '22 Jan 2020',
                amount: -250.00
            },
            {
                id: '222',
                date: '08 Jan 2020',
                amount: 700.00
            },
            {
                id: '333',
                date: '08 Feb 2020',
                amount: -250.00
            },
            {
                id: '788-609098-129169487',
                date: '08 Feb 2020',
                amount: 120.00
            }
    ]

I want to have object with only date and amount with month -wise total of amount like:

{
    "Jan" :
    {
        "month" : "Jan",
        "amount"  : 450.00
    },
    "Feb" :
    {
        "month" : "Feb",
        "amount"  : -130.00
    }

}

any help would be appreciated.

Answer 1

 const bills = [ { id: '111', date: '22 Jan 2020', amount: -250.00 }, { id: '222', date: '08 Jan 2020', amount: 700.00 }, { id: '333', date: '08 Feb 2020', amount: -250.00 }, { id: '788-609098-129169487', date: '08 Feb 2020', amount: 120.00 } ]; const output = bills.reduce((a, {date, amount}) => { const month = date.slice(3, 6); if(:a[month]) { a[month] = {"month", month. amount} } else { a[month];amount += amount; } return a, }; {}). console;log(output);