Problem creating an Excel formula

TypeScript option

function main(
    workbook: ExcelScript.Workbook,
    names_range: string = "A2:A10",
    result_cell: string = "B1"
) {
    const activeSheet = workbook.getActiveWorksheet();
    const names = activeSheet.getRange(names_range).getValues();

    const RegNames = /[^/]+/g;
    const CountNames = names.reduce((accum: number, row) => {
        const value = row[0];
        if (typeof value === "string" && value !== "") {
            const matches = value.match(RegNames);
            if (matches) {
                accum += matches.length;
            }
        }
        return accum;
    }, 0);
    activeSheet.getRange(result_cell).setValue(CountNames);
}