Simple numbered markers with Leaflet.js

I thought I’d look up how to create markers that are numbered with the excellent Leaflet.js. Perhaps surprisingly there is no built in method, but looking round the Web there are a few suggested ways of doing it. These all seemed rather over-engineered though so I decided to engage brain rather than just blindly copying. The following method works, and is a lot less complicated than anything else I’ve seen out there.

I wanted to achieve this (yes I know grey is not a good choice in this case, but it is what the user wanted):

To get markers like this first of all copy the Leaflet.js default marker image, which in 0.7.3 is here -> . I simply modified this using Paint.Net to be solid grey. Put the final image into your website/application.

Create a CSS class like this, obviously substituting your image path/name and font colour:

	background-image: url("images/number-marker-icon.png");

Then when creating your marker you need to add this code, putting the number in the ‘html’ parameter:

      var numberIcon = L.divIcon({
            className: "number-icon",
            iconSize: [25, 41],
            iconAnchor: [10, 44],
            popupAnchor: [3, -40],
            html: variable_containing_the_number        

      var marker = new L.marker([lat, long],
                                icon: numberIcon

And that’s all there is to it. Not quite sure why there are so many other elaborate methods out there, but maybe they work for use cases other than the one I had too.


Submitting a multipart AJAX form with CKEditor textarea

OK, the subject of this post is pretty niche, but that’s why I am posting about it because I do it so little I’d only forget about it for the next time!

With ASP.NET MVC if you want to allow a file upload on a form submitted by AJAX then you have to intercept the form submit event and do the submit it yourself via Javascript, rather than using MVC’s helpers. This is detailed in this useful Stackoverflow answer: How to do a aspnet mvc ajax form post with multipart form data

What the post doesn’t mention (as it wasn’t asked for!) was that if your form contains an instance of the popular rich text editor CKEditor then this code alone will not transfer the data the editor contains to the form. I think this must be because the CKEditor is waiting for the submit event to be triggered before it does the copy into the field.

It took a bit of digging, as I have not had to look at the CKEditor API before, but if you take the code from the above link as a start point, then add the following code to somewhere between the event.preventDefault() call and the ajax() call, it seems to work OK.

            for (instance in CKEDITOR.instances) {