JavaScript – Convert CSV to XLSX (Preferably Without Use of Library(s))

csvexceljavascriptsharepointxlsx

As the title says, I currently have a CSV file created from SharePoint list data and in order to display this information as a spreadsheet, I want to convert it to an Excel XLSX file. I prefer to do this without relying on a third-party library. At first, I started to use ActiveX objects to try to recreate and/or save the CSV as XLSX, but there's a limitation with that since I can't really use it in other browsers besides IE. I was thinking using Blob to somehow convert it? That's where I'm stuck.

function createCsv(data) {
    var result = "";

    if (data == null || data.length == 0) {
        return;
    }

    var columnDelimiter = ',';
    var lineDelimiter = '\n';

    var keys = Object.keys(data[0]);

    // spreadsheet header

    result += keys.join(columnDelimiter);
    result += lineDelimiter;

    // spreadsheet data

    data.forEach(function (obj) {
        var count = 0;

        keys.forEach(function (key) {
            if (count > 0) {
                result += columnDelimiter;
            }

            result += obj[key];
            count++;               
        });

        result += lineDelimiter;
    });

    return result;
}

function downloadCsv(csv) {
    if (csv == null) {
        return;
    }

    var filename = "test.csv";

    csv = "data:text/csv;charset=utf-8," + csv;

    var data = encodeURI(csv);

    console.log(data);

    var link = document.getElementById('csv');
    link.setAttribute('href', data);
    link.setAttribute('download', filename);

    console.log(link);

    //displayCsv(csv);
}

function displayCsv() {
    // using test csv here
    var message = "data:text/csv;charset=utf-8, yo, hey, lol";
    //var fileType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
    var fileType = "application/msexcel";

    var csvFile = new Blob([message], {type: fileType});
    var csvUrl = URL.createObjectURL(csvFile);

    console.log(csvFile);
    console.log(csvUrl);

}

CSV works fine with using the spreadsheet (by downloading and opening it in Excel), but I really need a way to display it as a spreadsheet on a webpage and not as text, so that's why I'm looking to convert it over. Since I'm using this within SharePoint then I can use a Excel web part to display the XLSX – it won't open CSV files like this though. Thanks in advance.

Best Answer

It would be quite the undertaking to try to manually try to do this without libraries. While OpenXML files are XML based at their core, they are also bundled/zipped.

I would recommend take a look at SheetJS. https://sheetjs.com/

You can take CSV as input, and write it back out immediately as XSLX.

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