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I have an array of objects (old_array) that needs to be merged to become (new_array)

old_array = [
 id: 'ffff55', name: 'f5', card: 'a', request: device: 0, bus: 1, ship: 21 ,
 id: 'vvvv44', name: 'v4', card: 'c', request: device: 3, bus: 10, ship: 2 ,
 id: 'cccc33', name: 'c3', card: 'a', request: device: 0, bus: 1, ship: 2 ,
 id: 'ffff55', name: 'f5', card: 'b', request: device: 32, bus: 31, ship: 32 ,
 id: 'cccc33', name: 'c3', card: 'e', request: device: 21, bus: 21, ship: 22 ,
 id: 'cccc33', name: 'c3', card: 'd', request: device: 4, bus: 1, ship: 2 ,
 id: 'vvvv44', name: 'v4', card: 'c', request: device: 13, bus: 11, ship: 12 
 ];

new_array = [
 id: 'ffff55', name: 'f5', unique_cards: 2, request: device: 32, bus: 32, ship: 53 ,
 id: 'vvvv44', name: 'v4', unique_cards: 1, request: device: 16, bus: 21, ship: 14 ,
 id: 'cccc33', name: 'c3', unique_cards: 3, request: device: 25, bus: 23, ship: 26 
 ];

• merge the objects with same id and name to a single object


• merge the nested request object (Sum of its values)


• map card to the number of unique cards (by id)

I've been trying for 4 days straight but this array manipulation was hard

My best attempt was trying to group the array of objects by id but it become more complex with many redundant values

groupByArray(xs, key) 
 return xs.reduce(function(rv, x) 
 let v = key instanceof Function ? key(x) : x[key];
 let el = rv.find((r) => r && r.key === v);
 if (el) 
 el.values.push(x);
 else 
 rv.push( key: v, values: [ x ] );
 
 return rv;
 , []);
 

groupByArray(old_array , 'id')

You can use the function reduce to group and the function Object.values to extract the grouped objects.

Inside of the reduce's handler, you need to loop over the request's keys in order to sum up each value.

let array = [ id: 'ffff55', name: 'f5', card: 'a', request: device: 0, bus: 1, ship: 21 , id: 'vvvv44', name: 'v4', card: 'c', request: device: 3, bus: 10, ship: 2 , id: 'cccc33', name: 'c3', card: 'a', request: device: 0, bus: 1, ship: 2 , id: 'ffff55', name: 'f5', card: 'b', request: device: 32, bus: 31, ship: 32 , id: 'cccc33', name: 'c3', card: 'e', request: device: 21, bus: 21, ship: 22 , id: 'cccc33', name: 'c3', card: 'd', request: device: 4, bus: 1, ship: 2 , id: 'vvvv44', name: 'v4', card: 'c', request: device: 13, bus: 11, ship: 12 ];
let result = Object.values(array.reduce((a, id, name, card, request) => 0) + request[k]); 
 return a;
, Object.create(null)));

result.forEach(o => delete o.card);

console.log(result);

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