javascript - Getting Node.appendChild error with leaflet

I am trying to add a popup function to some polygons. I've been consulting a few different tutorials trying to work it out and I'm concerned that I am getting conflicting instructions.

The map I have now is displaying perfectly. The next step for me is to add the popup when the polygon is clicked on. I keep getting the error "Argument 1 of Node.appendChild is not an object." I have no idea what this means. My only guess is that it has something to do with using a var within landscape.js to create the landscape.geojson, since that might not be creating it in the right way to use it for the popup.

Answer

The layer.bindPopup method is expecting a string, but you are passing it a numeric property. You can avoid the error by either using .toString():

function toAddPopup (feature, layer) {
        layer.bindPopup(feature.properties.metro_severePct.toString());
        }

or by appending your property to another string using the + operator, which will also convert the numeric value to a string:

function toAddPopup (feature, layer) {
        layer.bindPopup('Percent severe:' + feature.properties.metro_severePct);
        }