download_file

$("#download").on('click', function(e){
    var d_start = $("#id_date_start").val();
    var d_end = $("#id_date_end").val();
    var offenses = $("#id_offense").val();


    data = {
            d_s: d_start,
            d_e: d_end,
            off: offenses,
        }

    console.log(data);

    var iframe = document.createElement('iframe');
    iframe.style.display= 'none';
    document.body.appendChild(iframe);

    var iframeDoc = iframe.contentDocument || iframe.contentWindow.document;

    var form = document.createElement('form');
    form.action = '/map/csv';
    form.method = 'GET';

    var input = document.createElement('input');
    input.type = 'hidden';
    input.name = 'csvdata';
    input.value = data;

    form.appendChild(input);

    (iframeDoc.body || iFrameDoc).appendChild(form);

    form.submit();
});