How can i modify indexing in a single object in javascript-CodePudding

I have an object list to store indexes just like that:

const initialIndexes = {
  0: [0,1,2],
  1: [0,1]
}

At this point I have a highlightedResultIndex variable. It gives an index like this:

highlightedResultIndex = 0 - case 1
highlightedResultIndex = 4 - case 2
highlightedResultIndex = 2 - case 3
...

And I finally try to get the following results by highlightedResultIndex

For the case 1:

result = {
 0: 0, // index from initialIndexes
 1: -1
}

For the case 2:

result = {
  0: -1,
  1: 1  // index from initialIndexes
}

For the case 3:

result = {
 0: 2  // index from initialIndexes
 1: -1
}

Maybe there is an easy method or there may be a certain algorithm for this, but I didn't know how to research it so I wanted to write it here. I would be glad if you help.

EDIT:

Let me put here some of examples

// This is data from the server side.
const initialIndexes = {
  0: [0,1,2,3],
  1: [0,1,2],
  2: [0,1,2],
  3: [0,1,2,3,4]
}

// So, I need to index object like this by highlightedResultIndex variable

// highlightedResultIndex = 0
{
 0:0,
1:-1,
2:-1,
3:-1
}

//  highlightedResultIndex = 6
{
0: -1,
1:2,
2:-1,
3:-1
}

//  highlightedResultIndex = 10
{
0: -1,
1:-1,
2:-1,
3:0
}

CodePudding user response：

You could take the wanted index value and reduce it by the lenght of the arrays until it fits into an array.

const
    initialIndexes = { 0: [0, 1, 2, 3], 1: [0, 1, 2], 2: [0, 1, 2], 3: [0, 1, 2, 3, 4] },
    getIndices = n => Object.fromEntries(Object
        .entries(initialIndexes)
        .map(([key, array]) => {
            const value = n >= 0 && n < array.length
                ? array[n]                           // or just n
                : -1;

            n -= array.length;
            return [key, value]; 
        })
    );

console.log(getIndices(0));  // { 0:  0, 1: -1, 2: -1, 3: -1 }
console.log(getIndices(6));  // { 0: -1, 1:  2, 2: -1, 3: -1 }
console.log(getIndices(10)); // { 0: -1, 1: -1, 2: -1, 3:  0 }

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