function createCSV(selector){
    var contentString, $els, i,j, l,m, tmp,
        row = document.querySelectorAll(selector)

    for(i=0, l=$row.length; i<l; i++){
        $els = $row[i].children;
        tmp = [];
        for(j=0, m=$els.length; j<m; j++){
            tmp.push($els[j].innerText);
        }
        contentString += tmp.join(",")+"\n";
    }
    return contentString;
}
function download(data, opt){
    var a = window.document.createElement('a');
    a.href = window.URL.createObjectURL(new Blob([data], {type: opt.mimeType}));
    a.download = opt.filename;
    document.body.appendChild(a)
    a.click();
    document.body.removeChild(a)
}

download(createCSV("table tr"), {
    mimeType:'text/csv',
    filename: 'table.csv'
})