trying to split arrays into teo seperate lists, ending up in an error https://trycf.com/gist/2b4ce6bee40d1ff2522d69b27fddd393/acf2023?theme=monokai Error: Cannot access array element at position 19. on line 10 what is wrong in this

Because

arraySlice()

wants the length of the slice, not the length of the original array.

It's almost as if the error message actually tells one that, too. 🤔

that above code did not worked for me so i tried this way and it works, used the mid to figure out its len and then use it

<cffunction name="splitList" returntype="array">
        <cfargument name="list" type="string" required="yes">
        
        <cfset var arr = listToArray(arguments.list)>
        <cfset var len = arrayLen(arr)>
        <cfset var mid = int(len / 2)>
        
        <cfif len mod 2 eq 1>
            <cfset mid = mid + 1>
        </cfif>
        
        <cfset var firstHalf = arraySlice(arr, 1, mid)>
        <cfset var secondHalf = arraySlice(arr, mid + 1, len - mid)>
        
        <cfreturn [firstHalf, secondHalf]>
    </cffunction>

This is a good start, but I think you need to do some boundary checking. This errors if the list has zero or one elements. These were the first two tests I ran on it.

Great catch I did not considered it but I will add some more checks

might not be a consideration, but also

arraySlice()

is not quite as performant when dealing with large arrays