function update() {
    fetch('http://localhost:9050/api/ais')
        .then(function (response) {
            return response.json();
        })
        .then(function (data) {
            updateData(data);
        })
        .catch(function (err) {
            console.log('error: ' + err);
        });
    function updateData(data) {
        var table = document.getElementById('aisTable');
        for (var i = 0; i < data.length; i++) {
            let row_id = "row_" + data[i].MMSI;
            row = document.getElementById(row_id);

            if(row == null) { // not found, create new row
                row = document.createElement('tr');
                row.innerHTML = `<td>` + data[i].MMSI + 
                    `</td><td id="name_` + data[i].MMSI + `"/>` + 
                    `<td id="timestamp_` + data[i].MMSI + `"/>` + 
                    `<td id="lat_` + data[i].MMSI + `"/>` + 
                    `<td id="lon_` + data[i].MMSI + `"/>` + 
                    `<td id="imo_` + data[i].MMSI + `"/>` + 
                    `<td>` + data[i].IsClassB + `</td>`;
                table.appendChild(row);
            }
            
            // update existing row
            var td = document.getElementById("name_" + data[i].MMSI);
            td.innerHTML = data[i].Name;
            td = document.getElementById("timestamp_" + data[i].MMSI);
            td.innerHTML = data[i].LastUpdate;
            td = document.getElementById("lat_" + data[i].MMSI);
            td.innerHTML = data[i].Latitude;
            td = document.getElementById("lon_" + data[i].MMSI);
            td.innerHTML = data[i].Longitude;
            td = document.getElementById("imo_" + data[i].MMSI);
            td.innerHTML = data[i].IMO; 
        }
    }
}

function startup() {
    setInterval(function () { update(); }, 10000);
}