Wrap characters with dashes

Wraps each character in the selected cells with "---" (for example, "text" becomes "---t---e---x---t---"). Empty cells and cells that are already wrapped are skipped.

(function () {

    let selection = Api.GetSelection();

    selection.ForEach(function (cell) {
        let cellValue = cell.GetValue();

        // Skip empty cells
        if (cellValue === null || cellValue === undefined || cellValue === "") {
            return;
        }

        // Convert the cell value to a string
        cellValue = String(cellValue);

        // Skip cells that are already wrapped
        if (/^---(?:.---)+$/.test(cellValue)) {
            return;
        }

        // Wrap each character in the cell value with "---"
        let sTemp = "---";
        for (let c = 0; c < cellValue.length; c++) {
            sTemp += cellValue.charAt(c) + "---";
        }

        cell.SetValue(sTemp);
    });
})();

Methods used: GetSelection, ForEach, GetValue, SetValue

Reference Microsoft VBA macro code

Sub Example()
    Dim Cell As Range
    Dim sTemp As String
    Dim C As Integer
    For Each Cell In Selection
        sTemp = "---"
        For C = 1 To Len(Cell)
            sTemp = sTemp & Mid(Cell, C, 1) & "---"
        Next
        Cell.Value = sTemp
    Next
End Sub

Result