export html table to csv javascript

function downloadCSV(csv, filename) {
    let csvFile;
    let downloadLink;

    // csv file
    csvFile = new Blob([csv], { type: 'text/csv' });

    // Download link
    downloadLink = document.createElement('a');

    // File name
    downloadLink.download = filename;

    // Create a link to the file
    downloadLink.href = URL.createObjectURL(csvFile);

    // Hide download link
    downloadLink.style.display = "none";

    // Add the link to DOM
    document.body.appendChild(downloadLink);

    // Click download link
    downloadLink.click();
}

function exportTableToCSV(filename, separator) {
    const csv = [];
    const rows = document.querySelectorAll("table tr");

    for (let i = 0; i < rows.length; i++) {

        let row = [];

        const cols = rows[i].querySelectorAll("td, th");

        for (let j = 0; j < cols.length; j++)
            // Add double quote to make the value stay in the same column if is separated by comma
            row.push(`"${cols[j].innerText}"`);

        csv.push(row.join(separator));
    }

    // Download CSV file
    downloadCSV(csv.join("\n"), filename);
}

document.querySelector('button').addEventListener('click', () => {
    exportTableToCSV('filename.csv', ',');
});