How to iterate through the attributes of a feature in Leaflet?

Question

I receive polygons via the ESRI REST API with Leaflet. I want to iterate through all attributes of a feature in order to create a custom pop-up for it.

My code looks like this:

myLayer.on('click', function (evt) 
{
   feature = evt.layer.feature;
   //Here I want to iterate ...
}

I know that I can access the attributes like this:

feature.properties.myAttribute

But how can I iterate through all attributes?

Answer 1

If my understanding is correct, you want to read all properties of the given event layer, without knowing in advance which properties are set and available?

In that case, this is a simple JavaScript problem, for which you can use Object.keys(feature.properties) to get the array of available "attributes" in feature.properties. Then simply iterate over that array:

myLayer.on('click', function (evt) {
    var feature = evt.layer.feature,
        props = feature.properties,
        attrs = Object.keys(props),
        attribute, value;

    for (var i = 0; i < attrs.length; i += 1) {
        attribute = attrs[i];
        value = props[attribute];
        // use the value to do something...
    }
});

You could also use the for...in:

for (attribute in props) {
    value = props[attribute];
}