I am faced with a scenario where I have two arrays of objects with identical structures. Array 1 consists of elements like:
[
{
id: "1",
name: "XX",
displayName: "XX",
count: 12
},
{
id: "2",
name: "XX",
displayName: "XX",
count: 12
},
{
id: "3",
name: "XX",
displayName: "XX",
count: 12
}
]
Meanwhile, Array 2 contains elements as follows:
[
{
id: "1",
count: 2
},
{
id: "3",
count: 5
}
]
My goal is to create a new array with the same structure as Array 1, but with adjusted count values. The desired output should look like this:
[
{
id: "1",
name: "XX",
displayName: "XX",
count: 10
},
{
id: "2",
name: "XX",
displayName: "XX",
count: 12
},
{
id: "3",
name: "XX",
displayName: "XX",
count: 7
}
]
This means that if a matching ID is found in Array 2, the new count should reflect the difference between the two values. Otherwise, the count remains unchanged. I have attempted to solve this using the .reduce() method, but I am struggling with the logic. As I am relatively new to JavaScript, coming from a background in C99 and Python, I am seeking guidance on how to approach this problem.
I am avoiding the use of nested for loops for efficiency reasons. One potential solution I considered was to convert all count values in Array 2 to negative, and utilize a method I discovered on the same website. This method involves summing up integer attributes:
const sumItem = ({ id, ...a }, b) => ({
id,
...Object.keys(a)
.reduce((r, k) => ({ ...r, [k]: a[k] + b[k] }), {})
});
const sumObjectsByKey = (...arrs) => [...
[].concat(...arrs) // combine the arrays
.reduce((m, o) => // reduce the combined arrays to a Map
m.set(o.id, // add the item to the Map
m.has(o.id) ? subItem(m.get(o.id), o) : { ...o } // if the item exists in the Map, sum the current item with the one in the Map. If not, add a clone of the current item to the Map
)
, new Map).values()]
However, this approach does not feel elegant or optimal, and I believe I should focus on improving my understanding of map-related methods. Can anyone provide assistance with this issue?