In my Leaflet application (version 1.0.1 1.0.3) I connect to ArcGIS Server via the Esri Leaflet plugin. I load the layer as dynamic layer:

var layerUrl = "http://localhost:6080/arcgis/rest/services//service1/MapServer";
var layer1 = L.esri.dynamicMapLayer({ 
   url: layerUrl, 

I only load this layer when a checkbox is clicked:

if (checkBox.checked){

Now my goal is, to show the cursor as 'wait' during the layer is loading. So I add this line:

layer.on('loading' , cursorWait());

The cursorWait function is this:

function cursorWait() {
    document.body.className = 'wait';


.wait, .wait * { cursor: wait; }

Which works great, but now I get error messages on my console:

TypeError: h.fn is undefined  leaflet.js:5:4965
    fire                     file:///C:/folder1/Leaflet/LeafletLib/Leaflet/leaflet.js:5:4965
    _renderImage             https://cdn.jsdelivr.net/leaflet.esri/2.0.0-beta.7/esri-leaflet.js:5:10474
    _requestExport/<         https://cdn.jsdelivr.net/leaflet.esri/2.0.0-beta.7/esri-leaflet.js:5:17673
    _createServiceCallback/< https://cdn.jsdelivr.net/leaflet.esri/2.0.0-beta.7/esri-leaflet.js:4:24163
    bound                    self-hosted:916:17
    createRequest/httpRequest.onreadystatechange https://cdn.jsdelivr.net/leaflet.esri/2.0.0-beta.7/esri-leaflet.js:4:9620

My question is: does someone know why these error messages occur? What really bugs me, that they appear only if I add the layer.on('loading',..) line, but then it appears also when I zoom in or out, although I am calling this only when the checkbox is checked. Also it seems to print an error message for each tile (?).
Am I using the layer.on('loading',..) event wrong? Or is it a bug? Should I just ignore the error messages?

  • 1
    Please specify your Leaflet version. Also, be aware that using leaflet-src.js instead of leaflet.js will give you better debug info. – IvanSanchez Jun 26 '17 at 9:05
  • Thanks! I updated the post, I am currently using version 1.0.1. I will try leaflet-src.js and also maybe a newer leaflet version. – ylka Jun 26 '17 at 10:16
  • I have updated to version 1.0.3 and using leaflet-src now. The error is the same and I don't see more debug info :(. Where is it supposed to be? I am using firefox developer tools – ylka Jun 26 '17 at 11:59
  • No, the error can not be the same. You cannot see h.fn using leaflet-src.js. – IvanSanchez Jun 26 '17 at 12:09
  • Yes you are right. Now it is l.fn... but it does not give me more debug info :( – ylka Jun 26 '17 at 12:22

you can (and should) skip including the parentheses when you wire up your event listener to a named function.

layer.on('loading' , cursorWait); // not cursorWait()

it appears also when I zoom in or out, although I am calling this only when the checkbox is checked.

the 'loading' event is fired each and every time a new image is requested from the map service. this happens each time the map is panned/zoomed. (reference)

unrelated tangent: we have released 10 patches for esri-leaflet since 2.0.0-beta.7, any reason you aren't upgrading?

  • Thanks, leaving out the parenthesis did the trick, now I don't see any error messages. But the problem is now it is not wokring as expected, beacause the wait cursor appears only immediately before the layer is shown. (Like for a ms, sometimes you don't even see it.) About the version: IvanSanchez pointed out that I am using an outdated version of esri-leaflet and upgraded since then to 2.0.8. – ylka Jun 28 '17 at 7:35
  • yup. 'loading' is not the most appropriate event for you to listen for if you'd like to show a loading indicator for the duration of time between when the layer is first checked on and an image is painted for the first time. – John Gravois Jun 29 '17 at 3:27
  • so which event would you suggest? – ylka Jun 29 '17 at 7:18
  • Ok I figured it out. Thanks @John Gravois. Now I am calling the cursorWait() function immediately after the checkbox was checked, without listening to a layer event. I was apparently overcomplicating it. – ylka Jun 29 '17 at 7:25

I am posting this solution in case someone is trying to implement something similar like a loading indicator:

if (checkBox.checked){
    layer.on('load', function(){document.body.classList.remove("wait");});

function cursorWait() {
    document.body.className = 'wait';

The problem was that I was trying to listen to the loading event which in this case makes not much sense, I can just call the 'wait' cursor when the checkbox is checked.
Thanks to John Gravois for pointing me in the right direction

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