I have the following array of objects:
[{"id":0,"name":"Katy","age":22},
{"id":2,"name":"Lucy","age":12},
{"id":1,"name":"Jenna","age":45},
{"id":3,"name":"Ellie","age":34}]
I need to add another key into the objects (PaymentCategory) where whichever object has the lowest ID is added the key with value "Cash", the one with highest ID "Card", and everything in between "Cheque"; the array also must then be sorted by ID.
Hence required output would be:
[{"PaymentCategory":"Cash","id":0,"name":"Katy","age":22},
{"Payment Category":"Cheque","id":1,"name":"Jenna","age":45},
{"Payment Category":"Cheque","id":2,"name":"Lucy","age":12},
{"Payment Category":"Card","id":3,"name":"Ellie","age":34}]
How can we achieve this result in the most efficient way, i.e. fewest number of iterations, highest performance?
Here's what I tried:
const min = array.reduce((prev,curr)=> prev.id<curr.id?prev:curr)
const max = array.reduce((prev,curr)=> prev.id>curr.id?prev:curr)
min.PaymentCategory = "Cash"
max.PaymentCategory = "Credit"
const result =[min, max]
The problem with this is:
max, one for min.The following provided approach is straightforward and first does sort the items of a shallow array copy ([...sampleData]) in an ascending order ( .sort((a, b) => a.id - b.id) ) of id values.
The final task does map each (sorted) item in a way which creates a shallow copy ({ ...item }) and in addition creates a 'Payment Category' entry where the first item ( idx === 0 ) gets assigned the 'Cash' value, the last item ( (idx === arr.length - 1) ) gets assigned the 'Card' value, and all other get assigned the 'Cheque' value.
The entire approach does not mutate the originally provided data ...
const sampleData = [
{ id: 0, name: "Katy", age: 22 },
{ id: 2, name: "Lucy", age: 12 },
{ id: 1, name: "Jenna", age: 45 },
{ id: 3, name: "Ellie", age: 34 },
];
console.log(
'mapped `sampleData` items ...',
[...sampleData]
.sort((a, b) => a.id - b.id)
.map((item, idx, arr) => ({
...item,
'Payment Category': ((idx === 0)
&& 'Cash') || ((idx === arr.length - 1)
&& 'Card') || 'Cheque',
}))
);
console.log('unmutated `sampleData` ...', sampleData);.as-console-wrapper { min-height: 100%!important; top: 0; }The above approach in an even more readable way ...
const copyItemAndAugmentPaymentCategory = (item, idx, arr) => ({
...item,
'Payment Category': ((idx === 0)
&& 'Cash') || ((idx === arr.length - 1)
&& 'Card') || 'Cheque',
});
const compareItemIdPrecedenceAscending = (a, b) => a.id - b.id;
console.log(
[
{ id: 0, name: "Katy", age: 22 },
{ id: 2, name: "Lucy", age: 12 },
{ id: 1, name: "Jenna", age: 45 },
{ id: 3, name: "Ellie", age: 34 },
]
.sort(compareItemIdPrecedenceAscending)
.map(copyItemAndAugmentPaymentCategory)
);.as-console-wrapper { min-height: 100%!important; top: 0; }you can do like this
const array =[{"id":0,"name":"Katy","age":22},
{"id":2,"name":"Lucy","age":12},
{"id":1,"name":"Jenna","age":45},
{"id":3,"name":"Ellie","age":34}]
const arrayLength= array.length
const newA=array.map( (element,index) => { if (index===0) return {"PaymentCategory":"Cash", ...element}
else if ( index===arrayLength-1 )return {"PaymentCategory":"Card", ...element}
else return {"PaymentCategory":"Cheque", ...element}})check map method in arrays to learn more : https://learnjsx.com/category/2/posts/es6-mapFunction