Question

I’ve been doing web development for quite sometime and have never seen this behavior with JavaScript. This is the code I started out with:

function processLogin() {
    if (loginReq.readyState == 4) {
        var data = eval('(' + loginReq.responseText + ')');
        data = data.userData;
        var focus = data.team.focus.coordinates;
        thisTeam = new Team(data.team.id, data.team.missionId, data.team.name, data.team.operatingArea.coordinates[0]);
        if (data.team.zoomLevel != '') {
            thisTeam.zoomLevel = data.team.zoomLevel;
        }
        if (focus.length > 0) {
            thisTeam.focusLat = focus[1];
            thisTeam.focusLon = focus[0];
        }
        for (var i = 0; i < data.teams.length; i++) {
            var temp_team = new Team(data.teams[i].id, data.teams[i].missionId, data.teams[i].name, []);
            teams.push(temp_team);
        }
        var teamDropDownText = [];
        for (var j = 0; j < teams.length; j++) {
            if (thisTeam.teamId == teams[j].teamId) {
                teamDropDownText.push('<option value="' + teams[j].teamId + '" selected="selected">' + teams[j].name + '</option>');
            } else {
                teamDropDownText.push('<option value="' + teams[j].teamId + '">' + teams[j].name + '</option>');
            }
        }
        $('#addIncidentTeam').html(teamDropDownText.join(''));
        $('#editIncidentTeam').html(teamDropDownText.join(''));
        // When all this has finished, make the
        //      rest of the calls to get the rest of the data
        startTimer();
        downloadDevices();
        initializeMap();
    }
}

What I have written there isn’t that important, and let me explain why.

The line with the single semicolon after thisTeam.zoomLevel = data.team.zoomLevel; was giving me a syntax error in firebug. I read and re-read my code, and couldn’t figure out what I did wrong, so I put the semicolon on the same line as thisTeam.zoomLevel = data.team.zoomLevel and it told me it had a syntax error on the blank line!

To do another test, I moved this whole function to it’s own JavaScript file and put everything after that line on one line and even tried to condense some of the code above, so now it looks like this:

function processLogin() {
if (loginReq.readyState == 4) {
    var data = eval('(' + loginReq.responseText + ')');
    data = data.userData;
    var focus = data.team.focus.coordinates;
    thisTeam = new Team(data.team.id, data.team.missionId, data.team.name, data.team.operatingArea.coordinates[0]); if (data.team.zoomLevel.length > 0) { thisTeam.zoomLevel = data.team.zoomLevel; } if (focus.length > 0) { thisTeam.focusLat = focus[1];thisTeam.focusLon = focus[0];} for (var i = 0; i < data.teams.length; i++) { var temp_team = new Team(data.teams[i].id, data.teams[i].missionId, data.teams[i].name, []); teams.push(temp_team); } var teamDropDownText = []; for (var j = 0; j < teams.length; j++) { if (thisTeam.teamId == teams[j].teamId) { teamDropDownText.push('<option value="' + teams[j].teamId + '" selected="selected">' + teams[j].name + '</option>'); } else { teamDropDownText.push('<option value="' + teams[j].teamId + '">' + teams[j].name + '</option>'); } } $('#addIncidentTeam').html(teamDropDownText.join('')); $('#editIncidentTeam').html(teamDropDownText.join('')); /* When all this has finished, make the rest of the calls to get the rest of the data */ startTimer(); downloadDevices(); initializeMap(); var kmlLink = document.getElementById('kmlLink'); var geoserverLink = document.getElementById('geoserverLink') if (user_role.substring(0, 1) == 'M') { kmlLink.href = "https://www.intelink.gov/giatstldni/hermes/webservice/kml/download/M&" + thisTeam.missionId + "&48"; kmlLink.innerHTML = "https://www.intelink.gov/giatstldni/hermes/webservice/kml/download/M&" + thisTeam.missionId + "&48"; geoserverLink.href = "https://www.intelink.gov/giatstldni/geoserver/wms/kml?layers=hermes_all&cql_filter=mission_id+=+" + thisTeam.missionId; geoserverLink.innerHTML = "https://www.intelink.gov/giatstldni/geoserver/wms/kml?layers=hermes_all&cql_filter=mission_id+=+" + thisTeam.missionId;} else { kmlLink.href = "https://www.intelink.gov/giatstldni/hermes/webservice/kml/download/T&" + thisTeam.id + "&48"; kmlLink.innerHTML = "https://www.intelink.gov/giatstldni/hermes/webservice/kml/download/T&" + thisTeam.id + "&48"; geoserverLink.href = "https://www.intelink.gov/giatstldni/geoserver/wms/kml?layers=hermes_all&cql_filter=team_id+=+" + thisTeam.id; geoserverLink.innerHTML = "https://www.intelink.gov/giatstldni/geoserver/wms/kml?layers=hermes_all&cql_filter=team_id+=+" + thisTeam.id; } } }

I did this just to see what error I would get, I knew it wouldn’t work correctly. But now it’s telling me there’s an error on a line that doesn’t exist in the file! I get:

syntax error
[Break On This Error] (10 out of range 8)

I went and commented more code out and it just made it 10 out of range 6! I don’t understand!

Answer 1

I found the culprit. One of the values of the JSON returned was empty (no quotes or anything). Not a very helpful error message.