datefile = document.getElementById("datafiles").value;
numbername = document.getElementById("numbers").value;
datatype = document.getElementById("datatype").value;
//alert("Auslesen: " + datefile + " " + numbername);

_basepath = getbasepath(); 
fetch(_basepath + '/fileserver/log/data/' + datefile)
.then(response => {
    // handle the response
    if (response.status == 404) {
        alert("no log data available for "+dateString);
    }
    response.text()
    .then( result => {
        var lines = result.split("\n");
        var trace = {
        x: [],
        y: [],
        type: 'scatter'
        };