How to lock only dedicated cells via Excel JavaScript API

As documented here I tried to lock only some cells (all cells of a column in my case) but all cells of the whole document are locked and not only the cells of the range. I already tried to lock only some cells like "D1:D5" but again all cells are locked and not only these 5 cells.

This is my code:

function lockColumnHandler() {
    lockColumn("Sheet1", "D:D");
}

function lockColumn(sheetName, columnRange) {
    Excel.run(function (ctx) {
        var sheet = ctx.workbook.worksheets.getItem(sheetName);
        var range = sheet.getRange(columnRange);

        if (range) {
            range.format.protection.locked = true;
        }

        sheet.protection.protect({
            allowAutoFilter: true,
            allowDeleteColumns: true,
            allowDeleteRows: true,
            allowFormatCells: true,
            allowFormatColumns: true,
            allowFormatRows: true,
            allowInsertColumns: true,
            allowInsertHyperlinks: true,
            allowInsertRows: true,
            allowPivotTables: true,
            allowSort: true
        });

        return ctx.sync();
    })
    .catch(errorHandler);
}

The default state in Excel is that all cells are marked as locked (you can right-click on any cell in Excel, go to Format Cells->Protection and you will find "Locked" is ticked by default).

So in order to lock only these cells, you would have to unlock all cells of the sheet, except the ones you want to lock.