csvHtml5 custom export not working properly

Hi,

I have a problem with the customize function for the csv export.

Actually I have a page on my website where you can specify the csv export config (date format, decimal format, field separator, field boundary, etc.), so first I retreive this data, then I process the default csv string to match my config, by changing the field separator etc.

The processing works well, my custom csv is properly formatted.

Here is the code I use for the buttons :

buttons: [
    {
        extend: 'csv',
        filename: 'datatables_csv',
        customize: async function(csv)
        {
            const customCSV = await defaultCSVBuilder(csv);

            console.log(customCSV);

            return customCSV;
        }
    }
]

As you can see I pass the default csv string to my custom csv builder to make some processing. Howerver when I open the downloaded csv, the content is : [object Promise]

I don't understand why despite using async / await the promise doesn't seem to resolve. So I put one await sleep(5sec) inside my custom function, before the end, and as soon as I clicked the download button, the file was downloaded, then 5 seconds later my custom csv file was displayed in the console. So it seems that customize() is not waiting for my custom function to resolve.

I don't feel like I have made a mistake but there is probably something that I don't understand, your help is welcome!

(I based my custom function on the comment on this page : https://datatables.net/reference/button/csv)