From what I understood from your answers what you need is to filter the array:

Copyconst filteredArray = array.filter(element => {
    if (yourConditionIsTrue) { // if this element should be in the filteredArray
        return true;
    } else {
        return false
    }
});

Which can be done in one line:

Copyconst filteredArray = array.filter(element => conditionIsTrue);

This way your array remains untouched and you get a new array (filteredArray) only with the elements you need, but you don't mess up with the array you are iterating.

Try to use Array.from(data).slice.
It worked for me same on ReactJS.

You can use the function Array.prototype.map as follows.

Copyconst array = ["AdsAyush", "AdsFace", "AdsKicks", "AdsMac"];
const result = array.map(element => element.slice(3));

console.log(result);

In the map of HTMLCarousel you have referred to the current element as Item.
And in JSX, you have referred to <Item>. It causes React to search for a component named Item. Even if Item exists will be ignored due the current element variable also being Item.

TLDR: Only class names & component names should begin with a capital letter.

Now to render children inside a map, just do

{ children.slice(step * size, size) }

This should work. If not replace <Item> with <> (React Fragment).

This is because .slice does a shallow copy and does not copy nested objects. Since you are using two dimensional array, this is expected.

Use: const input = JSON.parse(JSON.stringify(linsys))

Shallow cloning does not copy nested objects. So if an object contains an object, your .slice will keep a reference to the original copy of that object rather than creating a copy. Hence, the value changes.

In case of a shallow copy-

• Objects will reflect change in the original place from where they were shallowly copied because they are stored as references (to their address in the Heap).
• Primitive data types will NOT reflect change in the original place because they are directly stored in the callstack (in Execution Contexts).

For example:

var a = [
    [1, 2],    // This still is referencing to the original reference 
    [5,7]
]