Need help to sort index pages using InDesign script

Something like the following should work

function convertArray(arr) {
    var i = 0;
    while (i < arr.length) {
        var start = i;
        while (i + 1 < arr.length && arr[i] + 1 === arr[i + 1]) {
            i++;
        }
        var end = i;
        if (end - start > 1) {
            arr[start] = arr[start] + 'ff';
            // Remove all elements in the middle of the sequence
            arr.splice(start + 1, end - start);
            i = start + 1; // Move to the next element after the modified one
        } else if (end - start === 1) {
            arr[start] = arr[start] + 'f';
            // Remove the second element in the sequence
            arr.splice(start + 1, 1);
            i = start + 1; // Move to the next element after the modified one
        } else {
            i++;
        }
    }
    return arr;
}

var arr = [5, 6, 7, 43, 45, 65, 66, 77, 98, 99, 100, 123, 155, 166];
convertArray(arr);
$.writeln(arr);

-Manan